Liverpool: Imperious Liverpool extended their Premier League home winning streak against Arsenal to six on Saturday with an easy 4-0 victory that lifted them to second in the table.
Sadio Mane met a perfect free-kick from Trent Alexander-Arnold in the 39th minute to plant a header across Arsenal goalkeeper Aaron Ramsdale for Liverpool's opening goal.
Ramsdale produced a string of spectacular saves to keep Juergen Klopp's silky strikers at bay. But he could do nothing to stop Diogo Jota skipping past him in the 52nd minute after a dreadful misplaced pass from Arsenal defender Nuno Tavares.
Inevitably, Mohamed Salah got in on the act with a close-range volley from a Mane cross in the 73rd minute, before Takumi Minamino came off the bench to turn in a cross from Alexander-Arnold with his first touch in the 77th.
Arsenal showed a few flashes of resistance and attacking spirit in the first half - not least from manager Mikel Arteta who squared up angrily with Klopp over a foul in an ugly touch-line exchange that earned both yellow cards.
But Liverpool totally deserved the victory and it could have been even bigger were it not for England international Ramsdale.
The win put Liverpool on 25 points, four points behind leaders Chelsea after 12 games. Arsenal are fifth on 20.
Manchester United suffered a fourth defeat in five Premier League games as they went down 4-1 at Watford to pile more pressure on manager Ole Gunnar Solskjaer.
The visitors were punished for a ragged first-half display and after a brief fightback they capitulated horribly at the end after defender and captain Harry Maguire was sent off.
Joshua King and Ismaila Sarr were both on target for Claudio Ranieri's side in the first half, while Sarr also had a twice-taken penalty saved by David De Gea, who later described United's display as a nightmare.
Substitute Donny van de Beek inspired a revival after the break and halved the deficit in the 50th minute but Maguire's clumsy tackle that earned him a second yellow card with 20 minutes remaining summed up their day.
Watford made absolutely sure of a crucial win with a grandstand finish as stoppage-time goals by substitute Joao Pedro and Emmanuel Dennis sparked noisy celebrations from the Vicarage Road faithful.
It was a dreadful capitulation by United who face a crucial week with a Champions League tie against Villarreal before a trip to table-topping Chelsea next weekend.
They are in seventh place with 17 points, 12 behind Chelsea, while 16th placed Watford have 13 points from 12 games.