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 when his precise cross was tapped home by Christian Pulisic.
- Premier League Table | Fixtures | Top scorers
- How the teams lined up
- Analysis: Premier League hits and misses
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 penalty 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 as Chelsea held on for a club-record equalling seventh consecutive away victory, leaving Watford bottom and without a league win after 11 games.
Watford: Foster (8), Janmaat (5), Kabasele (6), Dawson (6), Cathcart (5), Masina (6), Chalobah (6), Doucoure (6), Deulofeu (7), Pereyra (6), Gray (6).
Subs: Mariappa (6), Hughes (6), Femenia (5).
Chelsea: Kepa (7), Azpilicueta (6), Zouma (7), Tomori (7), Emerson (6), Jorginho (7), Kovacic (8), Willian (7), Mount (7), Pulisic (8), Abraham (8).
Subs: Hudson-Odoi (n/a), Batshuayi (n/a), James (n/a).
Man of the Match: Tammy Abraham
How Chelsea held on to move third
Chelsea started the day 16 places and 15 points ahead of Watford in the table - and the gulf between the two sides took just five minutes to surface. Jorginho's instinctive first-time through ball released Abraham in behind the static Watford backline, and the in-form striker notched his 10th goal of the season with a clinical lob over the on-rushing Foster.
Chelsea threatened to run away with contest inside the opening 20 minutes and would have done had it not been for the inspired Foster, who produced a fine reflex save to deny Abraham a second after a deflected Mason Mount shot fell in his path before a looping Pulisic header was tipped behind.
Watford's cause was hampered by the loss of captain Craig Cathcart to injury, but they nearly drew level on 39 minutes when from lax Chelsea defending allowed Deulofeu to drift in from the right and flash a low shot inches wide.
Andre Gray replaced the injured Tom Cleverley in Watford’s only change from their goalless draw with Bournemouth. Frank Lampard followed suit, making one change from Chelsea’s victory at Burnley as Emerson Palmieri made his first appearance since September in place of Marcos Alonso.
Normal service resumed before the interval, though, as a stunning fingertip save from Foster tipped a thunderous Mount drive onto the crossbar, keeping Watford in the game when Chelsea should have been out of sight.
A fine block from Fikayo Tomori prevented Andre Gray from capitalising on Chelsea surrendering possession early in the second half, but it wasn't long before Foster was called upon again to parry a near-post drive from Mount wide.
And the Chelsea pressure finally told on 55 minutes when Willian found Abraham down the right channel and his inch-perfect cross set up Pulisic for the simplest of tap-ins - his fourth goal in two league matches.
The outstretched leg of Foster denied Pulisic a quick-fire second and his continued efforts between the sticks were rewarded on 79 minutes when Jorginho was penalised for a trip on Deulofeu after a lengthy VAR consultation.
The Spaniard coolly sent Kepa the wrong way to set up a grandstand finale that saw Watford nearly snatch a point, but the Chelsea goalkeeper had the final word with a last-gasp save from his opposite number Foster that secured a deserved win for Frank Lampard's side.
What the managers said...
Watford head coach Quique Sanchez Flores: "The match was very tough. Whatever happened during the match, we had a chance to draw with the last moment. It was tough, they had a lot of chances and are a very strong team, but with the difficulties we have playing against tough teams, we still had the possibility to draw. When we are positive on the pitch and feel we are competitive and aggressive and forget about the situation in the table, we are OK, we are a good team and able to compete really well."
Chelsea boss Frank Lampard: "I'm enjoying watching us play at the moment, which is great. I'm blessed with good players. I want the team to have a lot of energy and to be difficult to play against. I want us to move the ball quickly, I want us to be unpredictable. We felt that there were balls which could take advantage of their high line, but the threat of playing behind should always be there and we did that spot on. The last ten minutes gave me grey hairs! We were over-confident (with Watford's goal). The game should have been well and truly gone."
Analysis: 'Chelsea are a joy to watch'
Sky Sports' Jamie Redknapp:
"Chelsea had so many chances, and then you end up hanging on. It might have ended up a point when they deserved three. It's a joy to watch, the young players are bedding in so well. They look so comfortable and they're playing such good football.
"It becomes infectious. They've got a nice balance. The two midfielders were at times magnificent. And nobody's talking about [N'Golo] Kante. I can only imagine what it's like in training trying to get the ball off those two."
Man of the Match - Tammy Abraham
Despite dominating for large periods at Vicarage Road, the mood in the Chelsea camp on departure from Vicarage Road would have been completely different had it not been for the clinical touch of Tammy Abraham. Chelsea were on the board with their first chance, thanks to Abraham, and when they eventually converted the second of a hatful of chances, you guessed it, Abraham was centre stage once more. Had the in-from frontman been on the end of the chances his team-mates squandered, Chelsea would have been home and hosed long before Watford's late rally raised a few pulses.
- Chelsea have won seven consecutive away games in all competitions - their joint-longest winning run on the road in the club's history (also seven between February-April 1989 under Bobby Campbell).
- Watford have failed to win any of their opening 11 games to a league season for the first time in their history (D5 L6). They are the first team to do so in the Premier League since QPR in 2012-13.
- Christian Pulisic has been directly involved in nine goals for Chelsea in all competitions this season (4 goals, 5 assists); only Tammy Abraham has been involved in more (12) - while eight of those nine goal involvements have come away from Stamford Bridge, including all four goals.
Watford travel to Norwich live on Friday Night Football, live on Sky Sports Premier League at 8pm. Chelsea entertain Ajax in the Champions League on Tuesday at 8pm before hosting Crystal Palace on Saturday at 12.30pm.