Michy Batshuayi scored twice as stuttering Chelsea came from behind to win at Stamford Bridge.
After Pedro’s fabulous strike gave the champions an early lead, Abdoulaye Doucoure levelled seconds before the interval.
Worse followed for Chelsea when Roberto Pererya put Watford ahead four minutes in the second half.
With Chelsea facing the prospect of a third consecutive league defeat, Batshuayi, on as a substitute, headed in Pedro’s 71st-minute cross.
Cesar Azpilicueta put them in front with four minutes remaining, nodding in Willian’s cross at the far post.
And in injury time, Tiémoué Bakayoko’s interception set up Batshuayi, who held off Miguel Britos and nudged the ball past Heurelho Gomes.
A Chelsea victory had seemed unlikely as they again struggled without the likes of the injured N’Golo Kante, although David Luiz and Bakayoko were passed fit despite picking up minor injuries in the Champions League draw with Roma in midweek.
Antonio Conte’s side faded badly after Pedro put them ahead in fine style in the 11th minute.
Eden Hazard pulled the ball back from the right and Pedro swept a first-time shot from near the edge of the penalty area beyond Gomes and in off the top of the far post.
Cesc Fabregas then missed a great chance to double the lead.
Doucoure was unable to cut out Alvaro Morata’s pass to the unmarked Fabregas, whose nonchalant attempt to lift the ball over Gomes was pushed away by the former Tottenham goalkeeper.
Doucoure, on the other hand, finished emphatically when the ball dropped to him after Chelsea were unable to clear Jose Holebas’ thrown-in from the right.
The Blues had a major left-off soon after the restart, when Richarlison missed a sitter by side-footing wide from close range after being found unmarked by Christian Kabasele’s low cross.
Richarlison quickly atoned, collecting Troy Deeney’s pass and laying the ball across to Pereyra, who slotted past keeper Thibaut Courtois.
But Richarlison was then guilty of a second appalling miss – and his misplaced header from six yards out proved to be costly for the Hornets.
Had they gone 3-1 down at a stage in the game when they were playing dismally, the outcome might have been very different, but Chelsea found a way back into the match and eventually prevailed.
Chelsea (3-4-3:) Courtois; Rudiger, Luiz, Cahill; Azpilicueta, Bakayko, Fabregas, Alonso; (Willian 68) Pedro (Zappacosta 86), Hazard, Morata (Batshuayi 60).
Subs not used: Caballero, Christensen, Ampadu, Musonda.
This post was last modified on 23/10/2017