Tammy Abraham scored one and set up another but Chelsea had to weather a late Watford rally to secure a 2-1 victory that lifts them up to third in the Premier League.
Abraham arrested a run of four games without a goal with a brilliant lofted finish inside five minutes at Vicarage Road – his seventh goal away from home this season – and then turned provider 10 minutes into the second half as his precise cross was tapped home by Christian Pulisic.
A spirited goalkeeping performance from Ben Foster – who made no fewer than eight saves – prevented Chelsea from extinguishing Watford’s challenge, which was boosted 10 minutes from time when a controversial VAR-awarded was converted by Gerard Deulofeu.
Watford threw everything at Chelsea in search of an unlikely point but were denied deep in stoppage-time as a towering header from goalkeeper Foster was denied by the fingertips of Kepa Arrizabalaga.
The results means Watford remain without a Premier League victory this season after 11 games, while Chelsea consolidate third place after a club-record seventh consecutive away victory.