Eden Hazard hit a brace as the Blues responded to their recent 1-0 defeat to Leicester City by taking all three points in a pulsating Boxing Day win at Vicarage Road - the Blues ran out 2-1 winners.
Hazard notched up his 100 and 101st goals for the Blues - the first, a classy run, and zip around Ben Foster before tucking the ball into the empty net, the second, a well rehearsed penalty after he was taken down by Foster.
Watford had equalised with the last touch of the first half, a wonderful volley by Roberto Pereyra.
Chelsea return to fourth place in the Premier League - leapfrogging Arsenal who briefly held the final Champions League position with their early evening draw at Brighton.
The west Londoners are now two points ahead of the Gunners and chasing down Manchester City.
Tree minutes in and Pedro was inches away from opening the scoring for the Blues. Sublime interchanges with Willian saw the Spain wide-man cut inside from the right and unleashed a low, left footer which zipped inches wide of ben Forster’s left upright.
Willian was next up - again a classy counter-attack saw they Brazilian cut through the Hornets defence but his effort hit the same post with Christian Kabasele, trying to intercept the ball crashing into it.
He came back on the pitch for two minutes before exiting the pitch, he clearly had not recovered from the clash with the woodwork - Adrian Mariappa replaced him on 16 minutes.
Jorginho thwarted Abdoulaye Doucoure on 27 minutes as the midfielder let fly from just inside the Chelsea penalty area. The Brazilian too a smack on his back for his fruitful endeavour.
An Antonio Rudiger error five minutes later allowed the home side’s to counter and Doucoure saw his shot sail high and wide of Kepa Arrizabalaga’s goal.
A massive error by Jorginho allowed another counter with Gerard Deulofeu opening up the Chelsea rearguard. He slid the ball to in-running Troy Deeney, But Luiz threw himself in front of the ball, deflecting it away from the goal for a corner.
Three minutes before the break and Pedro signalled he had to come off - he was holding his left hamstring. Callum Hudson-Odoi replaced him
Sensationally the Blues took the lead on the stroke of half-time. Mateo Kovacic snatched the ball in midfield, passed to Eden Hazard just inside his own half and off raced the Belgium. Foster raced out but the mercurial midfielder, playing as a false nine, rounded the goalkeeper and slotted home.
But the west Londoners could not hold onto their lead and following a short corner the ball was lofted across goal and Roberto Pereyra smashed home a low drive from just outside the Blues penalty area, gaining Arrizabalaga no chance as he dived forlornly to his left - it was the last kick of the half.
There were no other changes at half-time.
Chelsea got a penalty on 57 minutes after Jorginho’s perfect defence-splitter sent Hazard free. He attempted to round Foster again, Burt the stopper decided to foul him, giving referee Martin Atkinson the easiest decision he had to make, pointing to the spot.
hazard dusted himself down and cooly slotted the ball past Foster from the spot to register his 101st goal for the Blues.
Willian’s angled left-footer on 72 minutes from a Hazard pass was inches wide as the Blues went for the jugular.
Hudson-Odoi failed to make an impact and was replaced by Emerson with five minutes left on the clock.
Next up for the Blues is a visit to Selhurst Park to face Crystal Palace on December 29.
Chelsea: Arrizabalaga, Rudiger, Alonso, Jorginho, Kante, Hazard,Pedro, Kovacic, Willian, Azpilicueta, Luiz
Subs: Caballero, Fabregas, barkley, Giroud, Hudson-Odoi, Cahill, Emerson
Watford: Foster, Deulofeu, Deeney, Sema, Cathcart, Doucoure, Femenia, Holebas, Kasasele, Capoue, Pereira
Subs: Gomes, Mariappa, Cleverley, Success, Marina, Quina, Osaka
Referee: Martin Atkinson