Everton held on to earn their first win in five matches as Watford threw away a two-goal lead and Tom Cleverley missed an injury-time penalty for the visitors.
In a remarkable second half at Goodison Park which lasted 58 minutes, Cleverley had the chance to snatch a point but put his weak spot-kick wide.
The Hornets had taken a healthy lead thanks to goals from Richarlison and Christian Kabasele.
But they lost first-choice keeper Heurelho Gomes, who was taken off with a nasty head gash shortly before Kabasele’s goal, and it proved to be the turning point.
Gomes’ replacement Orestis Karnezis, on his Watford debut, was at fault for Everton’s first when he came rushing out and Oumar Niasse darted past him and bundled the ball home.
From the Toffees’ first corner of the game, Dominic Calvert-Lewin headed home to equalise, and Leighton Baines scored the winner from the spot after Jose Holebas brought down Aaron Lennon.
There was 12 minutes of injury time after the stoppage for Gomes plus treatment for a back problem for Kabasele, and Watford thought they had rescued a draw when Everton keeper Jordan Pickford brought down Richarlison, but it was not to be for Cleverley.
A second half to remember
The first half was a drab affair, with Watford failing to register a shot on target and Everton’s only real effort coming from Baines, who was denied by Gomes.
But the game came to life 30 seconds after the restart, when Toffees defender Michael Keane was dispossessed and Andre Gray set up Richarlison, who slotted home at the near post.
Although Gomes’ injury seemed serious, it looked as though Watford had not been affected by his loss as Kabasele netted their second with a powerful header from Holebas’ corner.
But then they capitulated. Greece international Karnezis, who has only played four times all season, all for his country, was definitely at fault for the first goal, and should have done better for the second.
And there is no doubt Cleverley’s last-gasp penalty was wasted, as he scuffed wide against his former club, meaning Watford fell to a third consecutive league defeat.