And that brings to a conclusion our coverage from Brighton. A job well done for Samoa.
Next up is Wales v Uruguay at the Millennium Stadium, which you can follow now by clicking here.
We'll see you there!
Samoa 25-16 United States
Victory lifts Samoa above Japan to the top of Pool B. Scotland, who play the Brave Blossoms on Wednesday, are the only team in the group yet to see any 2015 Rugby World Cup action.
Samoa 25-16 United States
United States' AJ MacGinty was successful with his two penalty attempts, but missed both conversion attempts. If he had kicked one of them his side would have earned a losing bonus point.
BBCCopyright: BBC
Full-time
BBC SportCopyright: BBC Sport
Full-time
Samoa 25-16 United States
George Clancy brings to a close this second Pool B match to a close. Tries from Tim Nanai-Williams and Ofisa Treviranus give Samoa victory over the United States.
Man of the Match - Nanai-Williams
Samoa 25-16 United States
Samoa full-back Tim Nanai-Williams is announced as man of the match. The clock is red.
Getty ImagesCopyright: Getty Images
Samoa 25-16 United States
And, in keeping with the theme of the game, a States forward infringes coming off his feet at the breakdown.
The match is Samoa's.
AFPCopyright: AFP
Samoa 25-16 United States
Samoa have the ball back again though, inside their own half and working through the phases.
They look to wind the clock down.
Samoa 25-16 United States
Samoa gather the restart, but are soon enough penalised for not releasing.
AJ MacGinty boots to touch. The United States have three minutes or so to at least rescue a losing bonus point.
AFPCopyright: AFP
Try - Baumann, missed con MacGinty
Samoa 25-16 United States
They do make it count! Chris Baumann wriggles his way over to keep the game alive.
Can AJ MacGinty do his bit from the tee? Unfortunately for the United States he can't, meaning they trail by nine points and with the clock very much against them.
AFPCopyright: AFP
Samoa 25-11 United States
Want to know why the United States are trailing? Well, one of the reasons is the fact they have conceded 11 penalties (red and black circles) compared to only four from Samoa.
BBCCopyright: BBC
Samoa 25-11 United States
The line-out is good, the States are two metres from the line and with a penalty advantage.
Can they make it count? They need to make it count...
Samoa 25-11 United States
We have seen a lot more from the American backs in the second half, even if the scoreboard doesn't reflect it, as Thretton Palamo beats the first tackle and offloads.
The United States are into the 22 - and win a penalty for a deliberate knock on by Alesana Tuilagi.
This time they head for touch.
Penalty - Stanley
Samoa 25-11 United States
United States concede their 11th penalty(!) of the match, which replacement Mike Stanley superbly lands from around 40 metres on the angle. Excellent kick.
AFPCopyright: AFP
Samoa 22-11 United States
That's remarkable from USA wing Takudzwa Ngwenya, who runs fully 40 metres plus unchallenged - but from one side of the pitch to the other, making hardly any ground whatsoever.
Samoa come back through Alesana Tuilagi, who completely piles through a Chris Wyles tackle. The sort of run that has become his brother Manu's trademark, but has always been Alesana's.
AFPCopyright: AFP
Samoa 22-11 United States
That's superb defence from Samoa, as a couple of players halt the progress of Thretton Palamo and manage to hold the American centre up, earning themselves the put-in at a scrum.
"Swing low, sweet chariot" echoes around the Brighton Community Stadium. Can the United States muster a challenge to this Samoan dominance?
Get Involved
#bbcrugby
They don't James, they really don't.
Getty ImagesCopyright: Getty Images
Samoa 22-11 United States
With 20 minutes left, Samoa's Ofisa Treviranus has already made 13 carries. The most by any player in the first five matches of the World Cup was Schalk Burger's 18 during South Africa's 32-34 defeat by Japan on Saturday.
All the while, Takudzwa Ngwenya has knocked on for the United States so Northampton Saints scrum-half Kahn Fotuali'i will insert at a scrum.
Samoa prime minister backs his country
Getty ImagesCopyright: Getty Images
Speaking before the match, Samoa prime minister Tuilaepa Sailele Malielegaoi said his side could go all the way at the World Cup.
"The thing is we should make the quarter-finals,” said Tuilaepa, who is also the president of the Samoa Rugby Union.
Speaking to the Samoa Observer, he added: “If we reach the quarter-finals, there is nothing stopping us from the reaching the semi-finals and so forth… you never know, we might get lucky.
“We can never discount that possibility.”
So far, so good today, anyway.
Samoa 22-11 United States
That's a little unlucky from Tim Nanai-Williams, who spilled the ball but then brilliantly recovered to gather before it lands.
At least that's how I saw it - but referee George Clancy decides he knocked it on so the packs will scrum down.
EPACopyright: EPA
Samoa 22-11 United States
A terrific mini-break down the right from Takudzwa Ngwenya, who we've not seen too much from today. The States are immediately caught offside though.
The penalty count continues to grow.
Samoa 22-11 United States
While AJ MacGinty successfully lands his three-pointer, it's been a mixed afternoon with the boot so far for Samoa's Tusi Pisi. He has been successful (green) with four of his five penalties, but missed (red) both of his conversion attempts in addition to his errant penalty.
BBCCopyright: BBC
Penalty - MacGinty
Samoa 22-11 United States
AJ MacGinty makes no mistake from almost directly in front of the posts to reduce the arreas.
The United States are back to within a couple of converted tries from being head. Sounds simple written down, but not so when presented with 15 Samoans in front of you.
ReutersCopyright: Reuters
Samoa 22-8 United States
United States number eight Samu Manoa bulldozers his way through a couple of tackles, and the men in white and blue give away a penalty from the resulting breakdown.
Samu Manoa versus Manu Samoa. The best Rugby World Cup tongue-twister around?
AJ MacGinty will go for goal...
Samoa 22-8 United States
As Samoa are taking control, USA are having to work hard to try to stay in the game. They have made 66 tackles, compared to 59 from Samoa. But crucially, USA have missed 21 tackles, while Samoa have only missed 13.
USA pay for ill discipline
Samoa 22-8 United States
Rob Stevens
BBC Sport at Brighton Community Stadium
USA coach Mike Tolkin will have been stressing the importance of discipline during the half-time break, as the Eagles have been punished after giving away several penalties.
They showed their class when captain Chris Wyles scored after great play by the backs, but Samoa have largely been in control.
Getty ImagesCopyright: Getty Images
Penalty - Tusi Pisi
Samoa 22-8 United States
Another America infringement at the breakdown, another penalty for Samoa, another three points for Tusi Pisi.
We can't seem to update that last graphic often enough.
AFPCopyright: AFP
Get Involved #bbcrugby
Sporting upsets
Following Japan's win over South Africa, we are asking was result the biggest shock in sporting history.
Send us your thoughts on this debate and the current match Samoa v USA, via #bbcsport.
Samoa 19-8 United States
USA coach Mike Tolkin won't be happy to see this graphic. The red and black circles show the eight penalties his side have conceded, in comparison to only two from Samoa (red and white circles).
It was that indiscipline that led to that second try, too.
BBCCopyright: BBC
Try - Treviranus, missed con Tusi Pisi
Samoa 19-8 United States
And from the line-out Samoa duly extend their advantage further still.
Having secured safe ball, Alesana Tuilagi pounces upon a little kick in behind, setting the platform for captain Ofisa Treviranus to go over.
Tusi Pisi misses the conversion again, but Samoa lead by 11.
Post update
England hooker Dylan Hartley, who was dropped from the World Cup squad, is cheering on his Northampton team-mates Samoa's Ken Pisi and Kahn Fotauli'i and ex-team-mate Samu Manoa, who has now joined Toulon.
ReutersCopyright: Reuters
Get Involved
#bbcrugby
Samoa 14-8 United States
But the Eagles are soon penalised for going off their feet at a ruck, allowing Tusi Pisi to kick for touch just outside the American 22.
Samoa 14-8 United States
USA will need more possession than they had in the first half if they are to turn this match around. Samoa had 58% of the ball and lead by six points.
BBCCopyright: BBC
The United States do make a lively start to the second period though, as full-back Blaine Scully leads an early attack.
Kick-off
Samoa 14-8 United States
George Clancy's whistle and Tusi Pisi's boot gets us under way once more.
For the record, Samoa are ranked 12th in the world and the United States 15th coming into this match. Will it go true to form?
Samoa 14-8 United States
Samoa's Reynold Lee-Lo needs to work on his tackling. In the first half, he attempted five tackles, but missed with four of them.
He could learn from team-mates Sakaria Taulafo and Maurie Fa'asavalu, who both successfully made six tackles each.
However, United States' Zachary Fenoglio leads the way with seven successful tackles.
The two sets of players are on their way back onto the pitch. Let's get stuck back in.
AFPCopyright: AFP
Listen live
Samoa 14-8 United States
We'll also be bringing you live text commentary on both of those matches right here on the BBC Sport website.
It looks like that's your Sunday afternoon sorted then.
Samoa 14-8 United States
.Copyright: .
Seamus Kelly, who set up that Chris Wyles try for the United States, tops the metres-gained chart at half-time.
More of the same will be required if the Eagles are to get back into this Pool B contest.
Get alerts with the BBC Sport app
Samoa 14-8 United States
Now is also a fine time to remind you that, if you're out and about, you can now get Rugby World Cup alerts straight to your phone via the BBC Sport app.
Aside from a bit of early drizzle during Friday's opening match at Twickenham, we've been more than a bit lucky with the weather this weekend, allowing for plenty of eye-catching, free-flowing rugby.
But how's it looking for the next few matches? You can find out by clicking here.
Get Involved via #bbcrugby
Samoa 14-8 United States
South Africa Sunday TimesCopyright: South Africa Sunday Times
While Samoa and the United States continue to do battle in Brighton, we've been asking you whether Japan's win over South Africa yesterday on this same ground was the biggest shock in sporting history.
Let us know what you think via #bbcrugby on Twitter.
Half-time
BBC SportCopyright: BBC Sport
Half-time
Samoa 14-8 United States
With the clock red, the USA decide to carry on with ball in hand. They're over halfway, but a knock-on means George Clancy will call time on that opening 40 minutes.
PACopyright: PA
Penalty - Tusi Pisi
Samoa 14-8 United States
And the fly-half duly splits the posts to extend Samoa's lead to six points.
The clock ticks towards half-time.
Samoa 11-8 United States
That is so sloppy from the States, as Mike Petri comes over a ruck but clearly plays Kahn Fotuali'i before his opposition scrum-half picks the ball up.
This looks very kickable for Tusi Pisi...
APCopyright: AP
Samoa 11-8 United States
The white diamonds represent the rucks won by Samoa and there are about twice as many of them compared to the black diamonds, showing those rucks won by United States.
Samoa have dominated the possession, but there is only three points between the sides after that Chris Wyles score.
BBCCopyright: BBC
Try - Wyles, missed con MacGinty
Samoa 11-8 United States
And they have a try! AJ MacGinty's initial break opened it all up for the United States, allowing Seamus Kelly to tee up Chris Wyles for a relatively simple finish from close range.
AJ MacGinty can't convert, but the Americans are right back into this.
AFPCopyright: AFP
Samoa 11-3 United States
The crowd, as far as I can recall, break out in the unmistakable "USA, USA, USA..." chant for the first time.
They steal a line-out inside their own half too, which they'll try to run from deep...
ReutersCopyright: Reuters
Penalty - MacGinty
Samoa 11-3 United States
AJ MacGinty lands the kick and the Eagles are up and running at the Rugby World Cup.
Samoa 11-0 United States
.Copyright: .
Samoa 11-0 United States
At long last, the United States are back on the attack! Former Leicester Tigers man Blaine Scully leads the charge, up towards the five-metre line, and Samoa can only infringe as they get back to the full-back.
AJ MacGinty will go for goal, rather than for touch.
Penalty - Tusi Pisi
Samoa 11-0 United States
Flanker Jack Lam is the latest Samoan to show his dancing feet, breaking the first tackle and gaining fully 30 metres. As the United States scramble back, they concede yet another penalty at the breakdown too - which Tusi Pisi slots with ease.
AFPCopyright: AFP
Samoa 8-0 United States
Samoan captain Ofisa Treviranus, who plays his club rugby with London Irish in the Premiership, is down receiving some treatment following a blow earlier in the move.
USA's scrum holds strong and AJ MacGinty clears - but still they're unable to escape their own half.
Samoa 8-0 United States
USA are 8-0 down but they have not been helped by their own poor discipline. They have already conceded five penalties inside the opening 20 minutes.
BBCCopyright: BBC
Samoa come forward again too - but this time it's a forward pass from Joe Tekori that halts that particular attack.
Try - Nanai-Williams, missed con Tusi Pisi
Samoa 8-0 United States
And Samoa have the try they deserve. Tusi Pisi creates it, sending the cutest of grubbers through with two USA defenders upon him, and Tim Nanai-Williams, cousin of New Zealand's Sonny Bill, slides over in the corner. Superbly worked.
Pisi can't convert, but it was his magic that made the try happen.
Getty ImagesCopyright: Getty Images
Here is Nanai-Williams pictured with his All Black cousin when the pair won the Super Rugby Championship with the Chiefs in 2012.
Samoa 3-0 United States
AJ MacGinty is down and receiving a wee bit of treatment, having been sent tumbling by Filo Paulo when trying to send in a kick and chase.
Referee George Clancy decides there's nothing untoward about the collision, so Samoa come forward once more, into the Eagles' 22.
Missed penalty - Tusi Pisi
Samoa 3-0 United States
Tusi Pisi's kick, from full 50 metres accounting for the angle, falls very short though, meaning the States are able to clear long - but inviting the Samoan backs to launch another counter-attack with ball in hand.
Samoa 3-0 United States
The United States have had to do the majority of the defending in the opening 15 minutes - and lock Greg Peterson is penalised for coming off his feet at a ruck, giving Tusi Pisi another shot for the posts...
Getty ImagesCopyright: Getty Images
Samoa 3-0 United States
So after 10 minutes of action in Brighton, Samoa have had 73% of the ball, with USA offering little as an attacking force.
BBCCopyright: BBC
Post update
Former All Blacks half-back Piri Weepu enjoying today's action...
AFPCopyright: AFP
Samoa 3-0 United States
That's beautifully done by Eagles number 10 AJ MacGinty, who pokes a lovely little grubber out of play just five metres from the Samoan line.
Samoa, in white shirts, blue shorts and white socks, can only clear out of play just past their own 22-metre line.
Samoa 3-0 United States
We've seen plenty of Samoa with ball in hand, but here come the States now, working it from left to right - but the move ends when Saracens wing and Eagles captain Chris Wyles sends a pass arrowing straight out of play.
A few moments later, Takudzwa Ngwenya gathers safely under the high ball, only to be absolutely clattered by Samoa's Alesana Tuilagi. Another huge hit.
Penalty - Tusi Pisi
Samoa 3-0 United States
And Tusi Pisi splits the posts to put Samoa ahead in the Brighton sunshine.
Getty ImagesCopyright: Getty Images
Samoa 0-0 United States
Back come Samoa, however, and the States are soon penalised for failing to roll away at a ruck. Tusi Pisi will have a shot at goal...
Samoa 0-0 United States
Manu Samoa have settled into the game nicely now, working through the phases inside opposition territory. Fly-half Tusi Pisi, brother of Northampton pair George and Ken, throws a cheeky little offload between his legs to cheers around the ground.
It all breaks down though, and AJ MacGinty clears for the United States.
Get Involved via #bbcrugby
We agree Daniel, There is no better way to spend a Sunday.
Samoa 0-0 United States
After that early break in play, we'll have a couple of scrums, the second from which the Samoan pack win a penalty as it collapses in a heap on the floor.
Samoa 0-0 United States
Goodness me, welcome to the Rugby World Cup, Rey Lee-Lo. Opposition centre Thretton Palamo goes hurtling into the Cardiff Blues-bound number 12, who bounces to the ground and stays down.
After some treatment, he's withdrawn for Mike Stanley. Lee-Lo's World Cup debut lasts 41 seconds.
Samoa 0-0 United States
Irish referee George Clancy is the man in the middle, and his whistle prompts United States fly-half AJ MacGinty to kick long. Immediately, his side are on the attack.
Post update
Samoa v United States (12:00 BST)
With the anthems done, it's time for the Samoans to perform their pre-match war dance, the 'Siva Tau'.
All part of the spectacle - and always enough to send shivers down the spine. This time it's led by the bellowing Newcastle Falcons wing Alesana Tuilagi to complete silence inside the stadium. Brilliant.
AFPCopyright: AFP
Get Involved via #bbcrugby
Don't forget, we're asking you today whether you think Japan's win over South Africa was the biggest shock in sporting history...
The two teams make their way onto the field at a packed Brighton Community Stadium.
The United States are draped in navy blue, Samoa in white and blue.
It looks a stunning day on the south coast.
Getty ImagesCopyright: Getty Images
The odds stacked against Samoa?
Samoa v United States (12:00 BST)
BBCCopyright: BBC
To help put Japan's win over South Africa into further context, prior to the World Cup kicking off my colleague Mike Henson investigated what it was like to be one of the smaller nations in the rugby union world, using Samoa as his case study.
In the feature he highlights the pay differential during last year's autumn international series, with Samoa's squad on approximately £500 a week, or around £70 a day, during their northern hemisphere tour - while each of the England players featuring in their match at Twickenham match £15,000.
Click here to read the rather wonderfully-crafted piece in full.
Post update
Samoa v United States (12:00 BST)
BBC SportCopyright: BBC Sport
In contrast to today's opponents, Samoa have plenty of Rugby World Cup pedigree.
They've twice reached the last eight of the competition, once in their previous guise as Western Samoa, and have picked up at least one win in every World Cup they've played in.
Their most notable victories in the tournament both came against Wales - famously beating them 16-13 in Cardiff in 1991, before repeating the trick eight years later, again in the Welsh capital.
Split loyalties for one couple
Samoa v United States (12:00 BST)
Rob Stevens
BBC Sport at Brighton Community Stadium
Anyone who was here in the ground for Japan's momentous win yesterday will be hoping for more of the same today.
Liz and Richard Wilson were cheering on the Brave Blossoms against South Africa, but they have split loyalties this morning.
She was born in Connecticut so is supporting USA, but he has opted to root for Samoa. Will they still be talking after the match?
BBC SportCopyright: BBC Sport
Post update
Samoa v United States (12:00 BST)
BBC SportCopyright: BBC Sport
The United States are competing in their seventh Rugby World Cup in England and Wales, but their record isn't one to envy.
They've won only three of their 21 pool matches, with two of those victories coming against Springbok-slayers Japan, and you imagine they'll do well to add too many to that tally in 2015.
The USA do, at least, have one claim to fame - they won the last rugby union Olympic gold medal to be awarded in 1924.
Line-ups
Samoa v United States (12:00 BST)
BBC SportCopyright: BBC Sport
Replacements: Phil Thiel, Oli Kilifi, Chris Baumann, Cam Dolan, Danny Barrett, Shalom Suniula, Folau Niua, Brett Thompson.
Line-ups
Samoa v United States (12:00 BST)
BBC SportCopyright: BBC Sport
Replacements: Viliamu Afatia, Motu Matu'u, Census Johnston, Faifili Levave, Alafoti Faosiliva, Vavao Afemai, Mike Stanley, Fa'atoina Autagavaia.
Team news
Samoa v United States (12:00 BST)
Samoa have made nine changes to the side that won the Pacific Nations Cup for their World Cup Pool B opener against the the United States.
Only two backs - Northampton scrum-half Kahn Fotuali'i and Newcastle wing Alesana Tuilagi - survive from the team that beat Fiji.
Samoa beat the Eagles 21-16 when they met at the Pacific Nations Cup in July.
The United States are captained by Saracens' Chris Wyles, with Samu Manoa - who has joined Toulon after four years at Northampton Saints - in the back row.
USA fans get into spirit
Samoa v United States (12:00 BST)
Rob Stevens
BBC Sport at Brighton Community Stadium
It's a beautiful autumnal morning in Brighton which will please the Samoan players, who complained during the week that it rained here on the south coast every time they trained.
Fans are enjoying the atmosphere outside the stadium, with plenty of USA flags on show, and a few Captain Americas milling around.
BBC SportCopyright: BBC Sport
Get Involved via #bbcrugby
Getty ImagesCopyright: Getty Images
Before we do get stuck into today's matches, it certainly won't do us any harm to ponder that Brave Blossoms triumph for a little longer yet.
Here's how the rest of the world reacted - but where did it rank for you in terms of the greatest upsets in sporting history? Can you think of a surprise that trumps it?
State your case via #bbcrugby on Twitter.
Post update
BBC SportCopyright: BBC Sport
After the mayhem of yesterday, we have three more World Cup matches to bring you throughout this afternoon.
Samoa and the United States kick us off at the Brighton Community Stadium, before Wales begin their campaign against Uruguay at the Millennium Stadium from 14:30 BST.
We head to Wembley for the final game of the day, where world champions New Zealand begin the defence of their title against Argentina at 16:45 BST.
Post update
Getty ImagesCopyright: Getty Images
The biggest shock in Rugby World Cup history? The biggest shock in rugby union history? The biggest shock in sport, ever?
If one thing is for certain, it's that Japan's amazing last-gasp victory over two-time world champions South Africa had us all asking those very questions on Saturday.
And the questions, no doubt, will continue today. But, all the while, the show must go on...
Live Reporting
Brendon Mitchell
All times stated are UK
Get involved

BBCCopyright: BBC 
BBC SportCopyright: BBC Sport 
Getty ImagesCopyright: Getty Images 
AFPCopyright: AFP 
AFPCopyright: AFP 
AFPCopyright: AFP 
BBCCopyright: BBC 
AFPCopyright: AFP 
AFPCopyright: AFP 
Getty ImagesCopyright: Getty Images 
Getty ImagesCopyright: Getty Images 
EPACopyright: EPA 
BBCCopyright: BBC 
ReutersCopyright: Reuters 
Getty ImagesCopyright: Getty Images 
AFPCopyright: AFP 
BBCCopyright: BBC 
ReutersCopyright: Reuters 
BBCCopyright: BBC 
AFPCopyright: AFP 
.Copyright: . 
BBC SportCopyright: BBC Sport 
South Africa Sunday TimesCopyright: South Africa Sunday Times 
BBC SportCopyright: BBC Sport 
PACopyright: PA 
APCopyright: AP 
BBCCopyright: BBC 
AFPCopyright: AFP 
ReutersCopyright: Reuters 
.Copyright: . 
AFPCopyright: AFP 
BBCCopyright: BBC 
Getty ImagesCopyright: Getty Images 
Getty ImagesCopyright: Getty Images 
BBCCopyright: BBC 
AFPCopyright: AFP 
Getty ImagesCopyright: Getty Images 
AFPCopyright: AFP View more on twitterView more on twitter 
Getty ImagesCopyright: Getty Images 
BBCCopyright: BBC 
BBC SportCopyright: BBC Sport 
BBC SportCopyright: BBC Sport 
BBC SportCopyright: BBC Sport 
BBC SportCopyright: BBC Sport 
BBC SportCopyright: BBC Sport 
BBC SportCopyright: BBC Sport 
Getty ImagesCopyright: Getty Images 
BBC SportCopyright: BBC Sport 
Getty ImagesCopyright: Getty Images
Latest PostSamoa 25-16 United States
And that brings to a conclusion our coverage from Brighton. A job well done for Samoa.
Next up is Wales v Uruguay at the Millennium Stadium, which you can follow now by clicking here.
We'll see you there!
Samoa 25-16 United States
Victory lifts Samoa above Japan to the top of Pool B. Scotland, who play the Brave Blossoms on Wednesday, are the only team in the group yet to see any 2015 Rugby World Cup action.
Samoa 25-16 United States
United States' AJ MacGinty was successful with his two penalty attempts, but missed both conversion attempts. If he had kicked one of them his side would have earned a losing bonus point.
Full-time
Full-time
Samoa 25-16 United States
George Clancy brings to a close this second Pool B match to a close. Tries from Tim Nanai-Williams and Ofisa Treviranus give Samoa victory over the United States.
Man of the Match - Nanai-Williams
Samoa 25-16 United States
Samoa full-back Tim Nanai-Williams is announced as man of the match. The clock is red.
Samoa 25-16 United States
And, in keeping with the theme of the game, a States forward infringes coming off his feet at the breakdown.
The match is Samoa's.
Samoa 25-16 United States
Samoa have the ball back again though, inside their own half and working through the phases.
They look to wind the clock down.
Samoa 25-16 United States
Samoa gather the restart, but are soon enough penalised for not releasing.
AJ MacGinty boots to touch. The United States have three minutes or so to at least rescue a losing bonus point.
Try - Baumann, missed con MacGinty
Samoa 25-16 United States
They do make it count! Chris Baumann wriggles his way over to keep the game alive.
Can AJ MacGinty do his bit from the tee? Unfortunately for the United States he can't, meaning they trail by nine points and with the clock very much against them.
Samoa 25-11 United States
Want to know why the United States are trailing? Well, one of the reasons is the fact they have conceded 11 penalties (red and black circles) compared to only four from Samoa.
Samoa 25-11 United States
The line-out is good, the States are two metres from the line and with a penalty advantage.
Can they make it count? They need to make it count...
Samoa 25-11 United States
We have seen a lot more from the American backs in the second half, even if the scoreboard doesn't reflect it, as Thretton Palamo beats the first tackle and offloads.
The United States are into the 22 - and win a penalty for a deliberate knock on by Alesana Tuilagi.
This time they head for touch.
Penalty - Stanley
Samoa 25-11 United States
United States concede their 11th penalty(!) of the match, which replacement Mike Stanley superbly lands from around 40 metres on the angle. Excellent kick.
Samoa 22-11 United States
That's remarkable from USA wing Takudzwa Ngwenya, who runs fully 40 metres plus unchallenged - but from one side of the pitch to the other, making hardly any ground whatsoever.
Samoa come back through Alesana Tuilagi, who completely piles through a Chris Wyles tackle. The sort of run that has become his brother Manu's trademark, but has always been Alesana's.
Samoa 22-11 United States
That's superb defence from Samoa, as a couple of players halt the progress of Thretton Palamo and manage to hold the American centre up, earning themselves the put-in at a scrum.
"Swing low, sweet chariot" echoes around the Brighton Community Stadium. Can the United States muster a challenge to this Samoan dominance?
Get Involved
#bbcrugby
They don't James, they really don't.
Samoa 22-11 United States
With 20 minutes left, Samoa's Ofisa Treviranus has already made 13 carries. The most by any player in the first five matches of the World Cup was Schalk Burger's 18 during South Africa's 32-34 defeat by Japan on Saturday.
All the while, Takudzwa Ngwenya has knocked on for the United States so Northampton Saints scrum-half Kahn Fotuali'i will insert at a scrum.
Samoa prime minister backs his country
Speaking before the match, Samoa prime minister Tuilaepa Sailele Malielegaoi said his side could go all the way at the World Cup.
"The thing is we should make the quarter-finals,” said Tuilaepa, who is also the president of the Samoa Rugby Union.
Speaking to the Samoa Observer, he added: “If we reach the quarter-finals, there is nothing stopping us from the reaching the semi-finals and so forth… you never know, we might get lucky.
“We can never discount that possibility.”
So far, so good today, anyway.
Samoa 22-11 United States
That's a little unlucky from Tim Nanai-Williams, who spilled the ball but then brilliantly recovered to gather before it lands.
At least that's how I saw it - but referee George Clancy decides he knocked it on so the packs will scrum down.
Samoa 22-11 United States
A terrific mini-break down the right from Takudzwa Ngwenya, who we've not seen too much from today. The States are immediately caught offside though.
The penalty count continues to grow.
Samoa 22-11 United States
While AJ MacGinty successfully lands his three-pointer, it's been a mixed afternoon with the boot so far for Samoa's Tusi Pisi. He has been successful (green) with four of his five penalties, but missed (red) both of his conversion attempts in addition to his errant penalty.
Penalty - MacGinty
Samoa 22-11 United States
AJ MacGinty makes no mistake from almost directly in front of the posts to reduce the arreas.
The United States are back to within a couple of converted tries from being head. Sounds simple written down, but not so when presented with 15 Samoans in front of you.
Samoa 22-8 United States
United States number eight Samu Manoa bulldozers his way through a couple of tackles, and the men in white and blue give away a penalty from the resulting breakdown.
Samu Manoa versus Manu Samoa. The best Rugby World Cup tongue-twister around?
AJ MacGinty will go for goal...
Samoa 22-8 United States
As Samoa are taking control, USA are having to work hard to try to stay in the game. They have made 66 tackles, compared to 59 from Samoa. But crucially, USA have missed 21 tackles, while Samoa have only missed 13.
USA pay for ill discipline
Samoa 22-8 United States
Rob Stevens
BBC Sport at Brighton Community Stadium
USA coach Mike Tolkin will have been stressing the importance of discipline during the half-time break, as the Eagles have been punished after giving away several penalties.
They showed their class when captain Chris Wyles scored after great play by the backs, but Samoa have largely been in control.
Penalty - Tusi Pisi
Samoa 22-8 United States
Another America infringement at the breakdown, another penalty for Samoa, another three points for Tusi Pisi.
We can't seem to update that last graphic often enough.
Get Involved #bbcrugby
Sporting upsets
Following Japan's win over South Africa, we are asking was result the biggest shock in sporting history.
Send us your thoughts on this debate and the current match Samoa v USA, via #bbcsport.
Samoa 19-8 United States
USA coach Mike Tolkin won't be happy to see this graphic. The red and black circles show the eight penalties his side have conceded, in comparison to only two from Samoa (red and white circles).
It was that indiscipline that led to that second try, too.
Try - Treviranus, missed con Tusi Pisi
Samoa 19-8 United States
And from the line-out Samoa duly extend their advantage further still.
Having secured safe ball, Alesana Tuilagi pounces upon a little kick in behind, setting the platform for captain Ofisa Treviranus to go over.
Tusi Pisi misses the conversion again, but Samoa lead by 11.
Post update
England hooker Dylan Hartley, who was dropped from the World Cup squad, is cheering on his Northampton team-mates Samoa's Ken Pisi and Kahn Fotauli'i and ex-team-mate Samu Manoa, who has now joined Toulon.
Get Involved
#bbcrugby
Samoa 14-8 United States
But the Eagles are soon penalised for going off their feet at a ruck, allowing Tusi Pisi to kick for touch just outside the American 22.
Samoa 14-8 United States
USA will need more possession than they had in the first half if they are to turn this match around. Samoa had 58% of the ball and lead by six points.
The United States do make a lively start to the second period though, as full-back Blaine Scully leads an early attack.
Kick-off
Samoa 14-8 United States
George Clancy's whistle and Tusi Pisi's boot gets us under way once more.
For the record, Samoa are ranked 12th in the world and the United States 15th coming into this match. Will it go true to form?
Samoa 14-8 United States
Samoa's Reynold Lee-Lo needs to work on his tackling. In the first half, he attempted five tackles, but missed with four of them.
He could learn from team-mates Sakaria Taulafo and Maurie Fa'asavalu, who both successfully made six tackles each.
However, United States' Zachary Fenoglio leads the way with seven successful tackles.
The two sets of players are on their way back onto the pitch. Let's get stuck back in.
Listen live
Samoa 14-8 United States
We'll also be bringing you live text commentary on both of those matches right here on the BBC Sport website.
It looks like that's your Sunday afternoon sorted then.
Samoa 14-8 United States
Seamus Kelly, who set up that Chris Wyles try for the United States, tops the metres-gained chart at half-time.
More of the same will be required if the Eagles are to get back into this Pool B contest.
Get alerts with the BBC Sport app
Samoa 14-8 United States
Now is also a fine time to remind you that, if you're out and about, you can now get Rugby World Cup alerts straight to your phone via the BBC Sport app.
To find out here click here.
Your Rugby World Cup forecast
Samoa 14-8 United States
Aside from a bit of early drizzle during Friday's opening match at Twickenham, we've been more than a bit lucky with the weather this weekend, allowing for plenty of eye-catching, free-flowing rugby.
But how's it looking for the next few matches? You can find out by clicking here.
Get Involved via #bbcrugby
Samoa 14-8 United States
While Samoa and the United States continue to do battle in Brighton, we've been asking you whether Japan's win over South Africa yesterday on this same ground was the biggest shock in sporting history.
Let us know what you think via #bbcrugby on Twitter.
Half-time
Half-time
Samoa 14-8 United States
With the clock red, the USA decide to carry on with ball in hand. They're over halfway, but a knock-on means George Clancy will call time on that opening 40 minutes.
Penalty - Tusi Pisi
Samoa 14-8 United States
And the fly-half duly splits the posts to extend Samoa's lead to six points.
The clock ticks towards half-time.
Samoa 11-8 United States
That is so sloppy from the States, as Mike Petri comes over a ruck but clearly plays Kahn Fotuali'i before his opposition scrum-half picks the ball up.
This looks very kickable for Tusi Pisi...
Samoa 11-8 United States
The white diamonds represent the rucks won by Samoa and there are about twice as many of them compared to the black diamonds, showing those rucks won by United States.
Samoa have dominated the possession, but there is only three points between the sides after that Chris Wyles score.
Try - Wyles, missed con MacGinty
Samoa 11-8 United States
And they have a try! AJ MacGinty's initial break opened it all up for the United States, allowing Seamus Kelly to tee up Chris Wyles for a relatively simple finish from close range.
AJ MacGinty can't convert, but the Americans are right back into this.
Samoa 11-3 United States
The crowd, as far as I can recall, break out in the unmistakable "USA, USA, USA..." chant for the first time.
They steal a line-out inside their own half too, which they'll try to run from deep...
Penalty - MacGinty
Samoa 11-3 United States
AJ MacGinty lands the kick and the Eagles are up and running at the Rugby World Cup.
Samoa 11-0 United States
Samoa 11-0 United States
At long last, the United States are back on the attack! Former Leicester Tigers man Blaine Scully leads the charge, up towards the five-metre line, and Samoa can only infringe as they get back to the full-back.
AJ MacGinty will go for goal, rather than for touch.
Penalty - Tusi Pisi
Samoa 11-0 United States
Flanker Jack Lam is the latest Samoan to show his dancing feet, breaking the first tackle and gaining fully 30 metres. As the United States scramble back, they concede yet another penalty at the breakdown too - which Tusi Pisi slots with ease.
Samoa 8-0 United States
Samoan captain Ofisa Treviranus, who plays his club rugby with London Irish in the Premiership, is down receiving some treatment following a blow earlier in the move.
USA's scrum holds strong and AJ MacGinty clears - but still they're unable to escape their own half.
Samoa 8-0 United States
USA are 8-0 down but they have not been helped by their own poor discipline. They have already conceded five penalties inside the opening 20 minutes.
Samoa come forward again too - but this time it's a forward pass from Joe Tekori that halts that particular attack.
Try - Nanai-Williams, missed con Tusi Pisi
Samoa 8-0 United States
And Samoa have the try they deserve. Tusi Pisi creates it, sending the cutest of grubbers through with two USA defenders upon him, and Tim Nanai-Williams, cousin of New Zealand's Sonny Bill, slides over in the corner. Superbly worked.
Pisi can't convert, but it was his magic that made the try happen.
Here is Nanai-Williams pictured with his All Black cousin when the pair won the Super Rugby Championship with the Chiefs in 2012.
Samoa 3-0 United States
AJ MacGinty is down and receiving a wee bit of treatment, having been sent tumbling by Filo Paulo when trying to send in a kick and chase.
Referee George Clancy decides there's nothing untoward about the collision, so Samoa come forward once more, into the Eagles' 22.
Missed penalty - Tusi Pisi
Samoa 3-0 United States
Tusi Pisi's kick, from full 50 metres accounting for the angle, falls very short though, meaning the States are able to clear long - but inviting the Samoan backs to launch another counter-attack with ball in hand.
Samoa 3-0 United States
The United States have had to do the majority of the defending in the opening 15 minutes - and lock Greg Peterson is penalised for coming off his feet at a ruck, giving Tusi Pisi another shot for the posts...
Samoa 3-0 United States
So after 10 minutes of action in Brighton, Samoa have had 73% of the ball, with USA offering little as an attacking force.
Post update
Former All Blacks half-back Piri Weepu enjoying today's action...
Samoa 3-0 United States
That's beautifully done by Eagles number 10 AJ MacGinty, who pokes a lovely little grubber out of play just five metres from the Samoan line.
Samoa, in white shirts, blue shorts and white socks, can only clear out of play just past their own 22-metre line.
Samoa 3-0 United States
We've seen plenty of Samoa with ball in hand, but here come the States now, working it from left to right - but the move ends when Saracens wing and Eagles captain Chris Wyles sends a pass arrowing straight out of play.
A few moments later, Takudzwa Ngwenya gathers safely under the high ball, only to be absolutely clattered by Samoa's Alesana Tuilagi. Another huge hit.
Penalty - Tusi Pisi
Samoa 3-0 United States
And Tusi Pisi splits the posts to put Samoa ahead in the Brighton sunshine.
Samoa 0-0 United States
Back come Samoa, however, and the States are soon penalised for failing to roll away at a ruck. Tusi Pisi will have a shot at goal...
Samoa 0-0 United States
Manu Samoa have settled into the game nicely now, working through the phases inside opposition territory. Fly-half Tusi Pisi, brother of Northampton pair George and Ken, throws a cheeky little offload between his legs to cheers around the ground.
It all breaks down though, and AJ MacGinty clears for the United States.
Get Involved via #bbcrugby
We agree Daniel, There is no better way to spend a Sunday.
Samoa 0-0 United States
After that early break in play, we'll have a couple of scrums, the second from which the Samoan pack win a penalty as it collapses in a heap on the floor.
Samoa 0-0 United States
Goodness me, welcome to the Rugby World Cup, Rey Lee-Lo. Opposition centre Thretton Palamo goes hurtling into the Cardiff Blues-bound number 12, who bounces to the ground and stays down.
After some treatment, he's withdrawn for Mike Stanley. Lee-Lo's World Cup debut lasts 41 seconds.
Samoa 0-0 United States
Irish referee George Clancy is the man in the middle, and his whistle prompts United States fly-half AJ MacGinty to kick long. Immediately, his side are on the attack.
Post update
Samoa v United States (12:00 BST)
With the anthems done, it's time for the Samoans to perform their pre-match war dance, the 'Siva Tau'.
All part of the spectacle - and always enough to send shivers down the spine. This time it's led by the bellowing Newcastle Falcons wing Alesana Tuilagi to complete silence inside the stadium. Brilliant.
Get Involved via #bbcrugby
Don't forget, we're asking you today whether you think Japan's win over South Africa was the biggest shock in sporting history...
Here come the teams...
Samoa v United States (12:00 BST)
The two teams make their way onto the field at a packed Brighton Community Stadium.
The United States are draped in navy blue, Samoa in white and blue.
It looks a stunning day on the south coast.
The odds stacked against Samoa?
Samoa v United States (12:00 BST)
To help put Japan's win over South Africa into further context, prior to the World Cup kicking off my colleague Mike Henson investigated what it was like to be one of the smaller nations in the rugby union world, using Samoa as his case study.
In the feature he highlights the pay differential during last year's autumn international series, with Samoa's squad on approximately £500 a week, or around £70 a day, during their northern hemisphere tour - while each of the England players featuring in their match at Twickenham match £15,000.
Click here to read the rather wonderfully-crafted piece in full.
Post update
Samoa v United States (12:00 BST)
In contrast to today's opponents, Samoa have plenty of Rugby World Cup pedigree.
They've twice reached the last eight of the competition, once in their previous guise as Western Samoa, and have picked up at least one win in every World Cup they've played in.
Their most notable victories in the tournament both came against Wales - famously beating them 16-13 in Cardiff in 1991, before repeating the trick eight years later, again in the Welsh capital.
Split loyalties for one couple
Samoa v United States (12:00 BST)
Rob Stevens
BBC Sport at Brighton Community Stadium
Anyone who was here in the ground for Japan's momentous win yesterday will be hoping for more of the same today.
Liz and Richard Wilson were cheering on the Brave Blossoms against South Africa, but they have split loyalties this morning.
She was born in Connecticut so is supporting USA, but he has opted to root for Samoa. Will they still be talking after the match?
Post update
Samoa v United States (12:00 BST)
The United States are competing in their seventh Rugby World Cup in England and Wales, but their record isn't one to envy.
They've won only three of their 21 pool matches, with two of those victories coming against Springbok-slayers Japan, and you imagine they'll do well to add too many to that tally in 2015.
The USA do, at least, have one claim to fame - they won the last rugby union Olympic gold medal to be awarded in 1924.
Line-ups
Samoa v United States (12:00 BST)
Replacements: Phil Thiel, Oli Kilifi, Chris Baumann, Cam Dolan, Danny Barrett, Shalom Suniula, Folau Niua, Brett Thompson.
Line-ups
Samoa v United States (12:00 BST)
Replacements: Viliamu Afatia, Motu Matu'u, Census Johnston, Faifili Levave, Alafoti Faosiliva, Vavao Afemai, Mike Stanley, Fa'atoina Autagavaia.
Team news
Samoa v United States (12:00 BST)
Samoa have made nine changes to the side that won the Pacific Nations Cup for their World Cup Pool B opener against the the United States.
Only two backs - Northampton scrum-half Kahn Fotuali'i and Newcastle wing Alesana Tuilagi - survive from the team that beat Fiji.
Samoa beat the Eagles 21-16 when they met at the Pacific Nations Cup in July.
The United States are captained by Saracens' Chris Wyles, with Samu Manoa - who has joined Toulon after four years at Northampton Saints - in the back row.
USA fans get into spirit
Samoa v United States (12:00 BST)
Rob Stevens
BBC Sport at Brighton Community Stadium
It's a beautiful autumnal morning in Brighton which will please the Samoan players, who complained during the week that it rained here on the south coast every time they trained.
Fans are enjoying the atmosphere outside the stadium, with plenty of USA flags on show, and a few Captain Americas milling around.
Get Involved via #bbcrugby
Before we do get stuck into today's matches, it certainly won't do us any harm to ponder that Brave Blossoms triumph for a little longer yet.
Here's how the rest of the world reacted - but where did it rank for you in terms of the greatest upsets in sporting history? Can you think of a surprise that trumps it?
State your case via #bbcrugby on Twitter.
Post update
After the mayhem of yesterday, we have three more World Cup matches to bring you throughout this afternoon.
Samoa and the United States kick us off at the Brighton Community Stadium, before Wales begin their campaign against Uruguay at the Millennium Stadium from 14:30 BST.
We head to Wembley for the final game of the day, where world champions New Zealand begin the defence of their title against Argentina at 16:45 BST.
Post update
The biggest shock in Rugby World Cup history? The biggest shock in rugby union history? The biggest shock in sport, ever?
If one thing is for certain, it's that Japan's amazing last-gasp victory over two-time world champions South Africa had us all asking those very questions on Saturday.
And the questions, no doubt, will continue today. But, all the while, the show must go on...