Norwich City moved clear of the bottom three with a last-gasp winner in a 3-2 victory over fellow strugglers Newcastle while Manchester City consolidated fourth spot after cruising to a 4-0 win at Bournemouth.
Alexis Sanchez, Alex Iwobi, Hector Bellerin and Theo Walcott scored the goals as Arsenal gained revenge over Watford for their recent FA Cup exit. The win kept Arsenal third but they are eight points behind Leicester.
"It doesn't matter how realistic our title challenge is - we can only believe in our own game," Arsenal manager Arsene Wenger said. "We just continue." Villa look doomed after they were hammered by Chelsea, for whom Ruben Loftus-Cheek, Alexandre Pato and Pedro (two) got the goals.
The managerless club, who also had Alan Hutton sent off late on, are 15 points from safety, with just six games to go, while Chelsea are 10th, just behind Liverpool.
"The club have to rebuild," Villa caretaker manager Eric Black said.
"We have come to a stage where we are altering certain things in the club and we have to come back. "We have to give the supporters something, not the other way round.
Newcastle thought they had done enough for a point when a penalty from Aleksandr Mitrovic made it 2-2 but Martin Olsson snatched a Norwich winner in injury time.
"We went through the other side against Liverpool, conceding in the last minute of stoppage time, so huge credit to the players," Norwich manager Alex Neil said.
"We have started to turn it around, that's seven points in three games (but) lots to do yet. "We have Crystal Palace and Sunderland to come which are as big as today was - if not bigger. But it's a good start."
The result means Norwich are four points clear of third-bottom Sunderland, who drew 0-0 with West Brom, and six ahead of Newcastle.
"The reaction of the team in the second half is a positive we can take," said Newcastle manager Rafael Benitez, whose side like Sunderland have a game in hand. "But it is not enough if we want to stay up.
"Every week you will see something a little bit better but we have to start winning."
Kevin de Bruyne scored on his return from injury as Manchester City stayed four points behind Arsenal in fourth. Fernando, De Bruyne and Sergio Aguero put City 3-0 up within 19 minutes and Aleksandr Kolarov finished it off with the fourth late on. West Ham lost ground in fifth after a 2-2 draw with Crystal Palace, with Dwight Gayle scoring the equaliser after the sending-off of Cheikhou Kouyate.
Stoke squandered a two-goal lead to draw 2-2 with Swansea in the day's other match.
-AAP