Right, that is all from us but head on over to our live text commentary on Barcelo...I mean Stoke versus Liverpool, which is under way now.
Arsenal manager Arsene Wenger: "We were not convincing offensively or defensively. I knew it it could be a tricky game, if you can't win the game, make sure you don't lose it.
"We know fitness wise, West Ham were ahead of us, they had already played competitive games. You never get the same intensity. Well done West Ham. We will respond to that accident.
"We bought and still lost the game today. We listen to people but we have to focus on the quality of our performance.
"You are never surprised in the Premier League. It is better if we don't talk too much and continue to work hard. The players were maybe too nervous and put too much pressure on themselves.
"Today we have been hurt mentally and it is a good opportunity to respond."
More from Slaven Bilic, speaking about 16-year-old Reece Oxford: “People were asking 'are you sure he is 16?' It was going to be a risk but he has got something. I thought if we need someone to sit in front of the defence who is cool and can be a third defender, but who can also play on the ball, I am very proud of him. Only on paper he is 16, he is a part of this new generation. Put it this was, if Messi was in front of me I would be more fazed than Reece."
West Ham manager Slaven Bilic: “We are all very pleased and it is great start for us. Not only for the three points but points against a team that are the title contenders. If you add to that a London derby, it makes it a even bigger win. This is very special. I am very proud of the second half performance.
“I know we have a good team and I know we have that in ourselves but I wasn’t sure how we were going to show it. Sam Allardyce left me a good team and left me some quality in the side. We are still short of a few players but we have a chance to do a good job in the Premier League."
I know, I know, you can't go talking about the table after one game, but what the heck. How often do you see Arsenal propping up the division?
Abdul Said: Well can Arsene Wenger listen this time? Buy buy or bye bye
Andrew Walker: Not won an opener since 2009, clearly preparation is not right from the coaches.
Olushola Popoola: People should stop slating Arsenal and give credit to Westham.. Good performance from the lads..
If Reece Oxford was this excited for last night's Match of the Day, imagine how he will be feeling about Match of the Day 2 tonight!
We knew we had it in us and we worked really hard. We can get a lot better but to come here and win, we are really happy. He is only 16 but he is bigger and better than me. He has the future ahead of him. Slaven has come and changed us, he has got us thinking positively so full credit to him.
It was a dream debut. I had Winston Reid and Angelo Ogbonna behind me encouraging me. It is an honour to be the youngest ever West Ham player. I found out last night I was playing, I was obviously happy.
Well, someone will certainly be sitting at home and smiling at that Arsenal result and performance...
"The easy thing would be to criticise Arsenal but they were well below par, especially after seeing them win the FA Cup and the pre-season they had. I would use the word gutsy to describe West Ham today. What Slave Bilic did do was let his players do something with the ball, he didn't just set up defensively. West Ham had numerous chances and it was a near perfect away day performance.
Well...who saw that result coming?
...and a great save by Adrian keeps Mesut Ozil at bay. Surely that is it?
James Tomkins smashes the ball away as another Arsenal attack breaks down...
A chance for Arsenal as Alexis Sanchez receives the ball just inside the area, opens up space for himself but he tries to place the ball into the bottom corner with a shot that lacks pace and Adrian collects.
Dimitri Payet springs the Arsenal defence and has the opportunity to add a third. He plays it safe, though, eating up valuable seconds by holding the ball on the right side of the Arsenal area.
Final change for West Ham as Modibo Maiga comes on for Diafra Sakho and is quickly into the thick of things as he shoots at Petr Cech - the first shot on target for West Ham that has not gone in.
Five added minutes for West Ham to hold on, or for Arsenal to stage an incredible fight back.
Good play from Diafra Sakho, who runs the ball into the corner before smacking it against Laurent Koscielny, winning the Hammers a corner.
Slaven Bilic knows this is not over yet, though, barking instructions from the edge of his technical area.
Now Santi Cazorla is denied as his powerful drive is pushed away by the diving Adrian.
Some Arsenal fans have had enough, making their way to the exits, looking back briefly in disgust. It has not been a good day for the hosts.
Tom, Kent: Having seen Reece Oxford in pre-season, I can see why he's started. Future England captain. You heard it here first!
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Theo Walcott sees a volley blocked, before Alex Oxlade-Chamberlain sends a fierce shot into the sidenetting.
The Gunners are pressing, but time is against them.
West Ham have picked out a pass, they have taken care with the football and made use of it. Too often clubs have visited here and not done that. It has come from the manager Slaven Bilic saying, 'go out and express yourselves'.
Youth is exchanged for experience as Reece Oxford makes way for Kevin Nolan. A very good Premier League debut for Oxford.
James Baker: 14 shots and 61% possession. West Ham are a very good side but Arsenal should be winning - but no one can put it in the net.
Rhyno: This is the beauty of he Premier League. Wake up call for top four candidates.
Paul Wade: West Ham have been brilliant so far. Payet will be in everyone's dream teams now. Looks class.
A break in play as Olivier Giroud and James Tomkins clash heads and both need treatment.
After a minute or two Giroud is back up on his feet. Tomkins takes a little longer, but a thumbs up from the physio to the West Ham bench suggests he is good to continue.
West Ham are edging closer to a first league win at Arsenal in eight years and 16-year-old Reece Oxford has more than played his part.
The teenager has been a busy presence in the Hammers half, helping to nullify Arsenal's infrequent attacks.
Theo Walcott races forward and shoots, deflected wide for a corner.
Once again the set piece lacks bite as the ball is sent into the area and bounces off Alexis Sanchez. The attempted clearance then hits the Chilean before West Ham clear.
Nacho Monreal goes in the book for Arsenal after a foul on Mark Noble. The West Ham skipper is down injured for a lengthy spell and Arsene Wenger is not happy. He wants things hurrying up.
It is Sanchez time.
Unable to play the full 90 minutes just yet, Alexis Sanchez is introduced for the final 25, with Mathieu Debuchy making way.
Big cheer from the Arsenal fans, can he make something happen?
For Arsenal, almost as bad as their defending has been their set-pieces - they have had a couple of free-kicks in promising positions but failed to make the most of them.
That's the case when Santi Cazorla sends in a free-kick from the left and Olivier Giroud meets it, but his header is straight at Adrian. Poor.
This is now a challenge for Slaven Bilic. What does he do? Put nine defenders on if you have to, just make sure you keep it at 2-0. What this could do for the confidence of his players will be unbelievable.
Scoring is Mauro Zarate's last action of the game as he makes way, somewhat reluctantly, for Matt Jarvis.
That change comes just after one for Arsenal as Theo Walcott was brought on for Francis Coquelin.
It was just far, far too easy for West Ham. Alex Oxlade-Chamberlain (15) caught out by Mauro Zarate and he fires in from outside the box.
This is the beauty of the Premier League, those coupon busting results. Arsenal didn't clear their lines and Mauro Zarate's early shot caught Petr Cech out. Did those West Ham supporters think they would be 2-0 after an hour? You are joking me. What a goal, what a performance.
My word! West Ham double their lead after shocking defending by Arsenal. Alex Oxlade-Chamberlain tries to move out of the defence with the ball but is too casual and allows Mauro Zarate to snatch possession.
The Argentine then strides towards the area before shooting low and his shot somehow creeps past Petr Cech and in at the near post.