Match ends, Watford 0, Liverpool 1.
Emre Can scored one of the goals of the season as Liverpool beat a poor Watford to capitalise on favourable results in the race for the Champions League.
The Reds midfielder met Lucas Leiva's delivery with a wonderful bicycle kick which flew into the top corner.
Watford rarely threatened, but almost snatched a point when Sebastian Prodl smashed against the bar in injury time.
Liverpool moved four points clear of Manchester United in fifth, while Watford remain 13th.
Jurgen Klopp's side know they will secure a top-four Premier League finish - and a return to the Champions League for the first time in three seasons - by winning their final three games.
The Merseyside club will host Southampton and relegation-threatened Middlesbrough at Anfield, either side of a trip to West Ham.
- Relive Liverpool's win at Vicarage Road
- Football Daily podcast - Can keeps Reds on course for top four
Liverpool take control of top-four race
Liverpool knew they would have slipped out of the top four before kick-off at Vicarage Road had their nearest challengers all won over the weekend.
But the Reds watched as Manchester City, Manchester United, Arsenal and Everton failed to crank up the pressure as they each dropped points.
It meant Liverpool's slender advantage remained intact - which even Klopp admitted he was surprised about before kick-off.
The German manager also stressed their rivals slipping up meant nothing if his side did not win their own games.
That they did, despite lacking fluency in a scrappy performance.
For much of a drab first half, during which forward Philippe Coutinho went off injured and was replaced by the returning Adam Lallana, the Reds rarely looked like threatening an organised Watford side.
Lallana, who had missed the previous five matches with a thigh injury, did clatter the crossbar with a wonderful volley after Hornets keeper Heurelho Gomes' poor punch.
However, that was soon surpassed by fellow midfielder Can.
"It was a massive win," said England international Lallana. "We have three games left now and it is in our hands. We must stay focused."
'You bet he Can!'
Reds midfielder Can illuminated what had been an insipid opening 45 minutes with a moment of inspiration shortly before the break.
The Germany international, 23, carefully eyeballed Lucas' pinpoint diagonal pass into the Watford area, showing extraordinary athleticism to meet the delivery with a perfectly executed bicycle kick which left Gomes stranded.
Can immediately raced towards the away dugout where he was mobbed by ecstatic team-mates and manager Klopp.
"That is the best goal I've ever scored," he said.
"I saw the space and I ran behind and my first thought was I wanted to head it, then I didn't think too much."
Team-mate Lallana added: "It was a worldy goal and worthy of winning any game."
Hornets lack sting as they aim to better last season
Watford midfielder Tom Cleverley warned Liverpool before kick-off that his side would still have "a big say" in the battle at the top of the table, with Walter Mazzarri's team rounding off their season with games against Manchester City, Chelsea and Everton.
Their priority is eclipsing the 13th-place finish and total of 45 points they secured in their top-flight return last year.
And Hornets skipper Troy Deeney said he "expected a reaction" after a tame defeat at Hull in their previous game. However, that failed to materialise.
Watford, for all their defensive resilience and organisation, offered little attacking spark as Liverpool controlled possession and territory before half-time.
The home side improved after the break as Etienne Capoue and Daryl Janmaat finally forced Reds keeper Mignolet into serious saves, before their best chance arrived in the final few seconds.
Liverpool, as they have done often this season, failed to deal with a set-piece into their box as Prodl met a flick-on with a fierce strike that cannoned back off the bar.
Despite their limp performance and daunting run-in, Watford are unlikely to be dragged into the relegation battle.
Mazzarri's side remain on 40 points - usually considered the benchmark for survival - eight above third-bottom Swansea who only have three games left.
Man of the match - Emre Can (Liverpool)
Watford go to defending champions Leicester City on Saturday (15:00 BST) as their tough run-in continues, while Liverpool host ninth-placed Southampton on Sunday (13:30).
|Watford's 2016-17 run-in|
|Sat 6 May||Leicester (A)|
|Fri 12 May||Everton (A)|
|Mon 15 May||Chelsea (A)|
|Sun 21 May||Man City (A)|
|Liverpool's 2016-17 run-in|
|Sun 7 May||Southampton (H)|
|Sun 14 May||West Ham (A)|
|Sun 21 May||Middlesbrough (H)|
Can can't stop scoring...
- Emre Can has scored five Premier League goals this season, more than twice as many as in his previous two campaigns combined.
- Lucas Leiva has three assists in his past five Premier League appearances, as many as in his previous 163 top-flight games.
- Liverpool have won three consecutive Premier League away games under Jurgen Klopp for only the second time.
- Liverpool skipper James Milner made his 450th Premier League appearance in this game, the 22nd player to reach this mark.
- Klopp named the same Liverpool starting XI for the third consecutive Premier League game, something he had only done once before, in December.
- Liverpool have scored 16 goals in the 15 minutes before half-time in league games this season, more than any other side, while Watford have shipped the most in this period (17).
- Watford conceded for the first time in four Premier League home games.
- Watford's opponents have hit the woodwork 20 times in the Premier League this season, more than any other side.
Watford manager Walter Mazzarri:
"I think that if you look at all of the Liverpool games that they play, they usually create five or six clear chances.
"We didn't concede them almost anything and had a couple of chances so overall it was a good performance.
"Usually I don't like to speak about luck but today we were completely unlucky.
"We didn't deserve to lose."
Liverpool manager Jurgen Klopp:
"We have pressure and it means you fight for something that is good. It is positive pressure. We want to stay focused.
"We don't expect for a second it will be easy to reach the Champions League. If people think we have the three points against Southampton they can not have seen Southampton this season.
"We didn't play perfect against Watford and a draw would have been hard to accept, but we got the three points and that is all that the lads deserved."
- 5PrödlBooked at 48mins
- 3BritosSubstituted forKabaseleat 19'minutes
- 7N AmrabatSubstituted forOkakaat 85'minutes
- 29CapoueBooked at 69minsSubstituted forSuccessat 73'minutesBooked at 90mins
- 21LeivaBooked at 44mins
- 27OrigiSubstituted forSturridgeat 84'minutes
- 10CoutinhoSubstituted forLallanaat 13'minutesSubstituted forKlavanat 87'minutes
- Craig Pawson
- Shots on Target
Second Half ends, Watford 0, Liverpool 1.
Isaac Success (Watford) is shown the yellow card for a bad foul.
Daniel Sturridge (Liverpool) wins a free kick in the attacking half.
Foul by Isaac Success (Watford).
Sebastian Prödl (Watford) hits the bar with a left footed shot from the left side of the box. Assisted by Stefano Okaka with a headed pass.
Attempt missed. Daryl Janmaat (Watford) right footed shot from outside the box misses to the left. Assisted by Tom Cleverley with a cross.
Foul by Lucas Leiva (Liverpool).
M'Baye Niang (Watford) wins a free kick in the attacking half.
Offside, Watford. Daryl Janmaat tries a through ball, but Stefano Okaka is caught offside.
Corner, Liverpool. Conceded by Heurelho Gomes.
Attempt saved. Daniel Sturridge (Liverpool) right footed shot from the centre of the box is saved in the centre of the goal.
Corner, Liverpool. Conceded by Heurelho Gomes.
Attempt saved. Joel Matip (Liverpool) right footed shot from the right side of the box is saved in the centre of the goal. Assisted by Georginio Wijnaldum.
Offside, Watford. Tom Cleverley tries a through ball, but Troy Deeney is caught offside.
Substitution, Liverpool. Ragnar Klavan replaces Adam Lallana.
Offside, Watford. Tom Cleverley tries a through ball, but Adrian Mariappa is caught offside.
Foul by Dejan Lovren (Liverpool).
Stefano Okaka (Watford) wins a free kick in the attacking half.
Substitution, Watford. Stefano Okaka replaces Nordin Amrabat.