Liverpool's midfielder Emre Can connects with this overhead kick to score against Watford at Vicarage Road Stadium in Watford, north of London on May 1, 2017Liverpool's midfielder Emre Can connects with this overhead kick to score against Watford at Vicarage Road Stadium in Watford, north of London on May 1, 2017 (AFP Photo/Adrian DENNIS)
The Germany midfielder's fifth goal of the season took Liverpool three points above fourth-place City, albeit having played a game more, inching Jurgen Klopp's side closer to Champions League qualification.
"The goal was spectacular, of course," Liverpool manager Klopp told Sky Sports.
"It was clear we have to work and that is what we did. It won't be easy for anyone to win here.
"We needed a bit of luck, but we worked hard for it."
It was Liverpool's third successive away win and got them back on track after a 2-1 home defeat by Crystal Palace on their previous outing had ended a seven-game unbeaten streak.
The only disappointment for the men in red at Vicarage Road was the early departure of playmaker Philippe Coutinho with what Klopp confirmed was a dead leg.
Walter Mazzarri's Watford remain 13th, having been denied a last-gasp equaliser when centre-back Sebastian Prodl's crisp effort thudded against the crossbar.
"We didn't deserve to lose," said Mazzarri.
"Their wonder goal means nothing is going on our side because the first real chance they had, and it wasn't really a chance, they took it."
M'Baye Niang registered an early shot on target for the hosts, but a sleepy start to the game was remarkable more for injuries than penalty-box action.
Coutinho came off second-best in an early collision with recalled Watford defender Adrian Mariappa.
- Success supplies fizz -
The Brazil international soldiered on until the 13th minute before giving way for Adam Lallana, who came on to make his first appearance after a month out with a groin injury.
Six minutes later Watford were forced into a change of their own when defender Miguel Britos signalled that he was unable to continue, which brought Christian Kabasele into the fray.
Liverpool went close with a couple of efforts from distance, Can extending Heurelho Gomes from range and Lallana rattling the bar with a stunning 20-yard volley after Gomes had punched clear.
The visitors were toiling, their lack of ideas exposed when Lucas Leiva received a 44th-minute booking for a totally unconvincing attempt to win a penalty off Tom Cleverley.
But two minutes into stoppage time Liverpool went ahead with a Goal of the Season contender.
Lucas flighted a pass into the box and with Nordin Amrabat standing off, Can launched himself into a magnificent scissors kick from 15 yards out that catapulted the ball into the top-left corner.
"That is the best goal I've ever scored," Can said.
Buoyed by the German's moment of brilliance, Liverpool set about putting the game to bed in the second half.
Gomes had to box away a James Milner free-kick and twice saved from Divock Origi, palming away a curling effort and then standing up well to thwart the Belgian striker in a one-on-one.
It took Watford until the 68th minute to register another shot on target.
Etienne Capoue's rising effort from distance was tipped over by Simon Mignolet, only for the officials to award a goal-kick, sparking a furious Watford reaction that saw Capoue booked for dissent.
The introduction of 21-year-old Nigerian Isaac Success gave Watford some attacking fizz and Daryl Janmaat almost caught Mignolet out with a curling effort from wide on the left.
Liverpool might have won more comfortably had Gomes not saved from Joel Matip and substitute Daniel Sturridge, but they were indebted to the woodwork for foiling Prodl at the death.