Seven goals were netted in a thrilling contest at Stamford Bridge, as ten-man Watford were edged out 4-3 by Premier League Champions Chelsea on Monday night.
Blues skipper John Terry put the Blues ahead, however a seventh strike of the season from Étienne Capoue got the Hornets back on level terms.
Goals either side of the half from Cesar Azpilicueta and Michy Batshuayi put the home team in a commanding position, but back came the Hornets with Daryl Janmaat netting a fine individual effort.
Belief grew in the Golden Boys' ranks, and with his third touch after coming off the bench, Stefano Okaka had them level.
Just as it looked like the points would be shared, substitute Cesc Fabregas fired home the winner in the 88th minute.
Nordin Amrabat, Tom Cleverley & M'Baye Niang replaced Christian Kabasele (thigh injury), Stefano Okaka & Troy Deeney at the Bridge, as Walter Mazzarri made three changes to the side beaten 1-0 at Everton.}
That left M'Baye Niang to lead the line against a much changed Chelsea XI, which included Nathaniel Chalobah, Nathan Aké and Kenedy.
After a relatively quiet and uneventful first 20 minutes, the game exploded into action.
Departing Chelsea skipper Terry sliced home from close-range after a loose ball from Willian’s corner fell kindly.
Terry turned from hero to villain in a matter of moments as Capoue met his poor defensive clearance, and headed home over Asmir Begovic to shock the Champions.
Eden Hazard nearly put the Blues back ahead just after the half-hour mark. The Belgian took Willian’s long pass in his stride before advancing into the area and dragging a shot inches wide of Heurelho Gomes’ goal.
After Kenedy forced Gomes into a smart save at his near-post, Azpilicueta then fired home from the edge of the area.
The initial corner was cleared only to the edge of the box, where the Spaniard drove accurately into the corner.
The hosts made a fast start after the break, with Batshuayi adding a third. A loose ball fell for Aké, who unselfishly played across for the young Belgian, who slotted home his second goal of the season against the Hornets.
Watford didn’t let their head drops though, reducing the deficit to one within minutes. A fine solo run from Janmaat saw him cut in from his left-sided position, before bending the ball expertly past Begovic.
A couple of fine stops from Gomes kept it at three, firstly keeping out Batshuayi, before superbly getting down to tip Azpilicueta’s drive wide.
Okaka was introduced by Mazzarri with 20 minutes to go, and he had an instant impact as he levelled proceedings.Tom Cleverley’s deep cross caused problems in the area, and Okaka was on-hand to confidently fire home the loose ball.
Attacking changes from Antonio Conte saw Pedro and Fabregas enter the field, and it was the latter who scruffily notched the winner from the edge of the area.
Sebastian Prödl was sent-off for a second bookable offence in the dying minutes, as the Hornets left London empty handed.
CHELSEA: Begovic (GK), Zouma, Terry (c), Aké, Azpilicueta, Kante, Chalobah (Fabregas, 78), Kenedy (Aina, 74), Willian, Batshuayi (Pedro 83), Hazard.
Subs not used: Eduardo, Alonso, Cahill, Costa.
Goals: Terry (22), Azpilicueta (36), Batshuayi (49), Fabregas (88).
Booked: Aké (29), Chalobah (58).
HORNETS: Gomes (GK) (c); Mariappa, Prödl, Holebas; Amrabat, Cleverley, Behrami, Doucouré, Janmaat; Capoue (Deeney 89); Niang (Okaka, 71),
Subs not used: Pantilimon (GK), Mason, Eleftheriou, Zúñiga, D Pereira.
Goals: Capoue (24), Janmaat (51), Okaka (74).
Booked: Holebas (3), Amrabat (10), Prödl (82), Deeney (90), Okaka (90).
Sent-off: Prödl (90).