Vicarage Road has witnessed some special nights down the years. It has another one to add to the list after Watford produced an astonishing finale to dismantle 10-man Chelsea 4-1 and get Javi Gracia’s reign at the Hornets’ home off to a start few would have dreamed of beforehand.

Watford would have been worthy winners had they had not added to Troy Deeney’s penalty at the end of the first half. But the catalyst for the memorable ending was, ironically, a fine equaliser from Eden Hazard with eight minutes of normal time remaining.

The Hornets have not responded well to setbacks at times this season. But their reaction on this occasion was fantastic as Daryl Janmaat, Gerard Deulofeu and Roberto Pereyra all netted superb goals to send Vicarage Road into a collective frenzy.

In the final analysis, the outcome was only three points and Gracia’s men are still too close to the drop zone for comfort. But the psychological effect of a victory of this nature given the supposed calibre of the opposition was considerable and gives Watford a superb springboard for the remainder of the campaign.

Watford had been the better side since the opening whistle, playing with greater intensity and attacking endeavour but their cause was to be helped when their opponents were reduced to 10 men with an hour to go after Tiemoue Bakayoko picked up two yellow cards within the space of five minutes.

The Hornets deserved to be in front before the interval and they duly make the breakthrough when Deeney converted a penalty after Thibaut Courtois was adjudged to have brought down Deulofeu by referee Mike Dean.

Chelsea did improve after the break – in truth, it would have been hard for them to get too much worse – but it was their opponents who continued to create the chances with Deulofeu, the rejuvenated Richarlison and Abdoulaye Doucoure all going close.

But after Hazard’s equaliser, Vicarage Road was to witness a 10 to 15-minute spell that will live long in the memory of all Hornets’ fans who witnessed it.

Watford’s injury curse struck again before the match as Christian Kabasele became the latest player to succumb to a hamstring injury, while Tom Cleverley was also ruled out with the same problem, having been forced off early at Stoke City.

Those were the only two changes from the goalless draw but the return of Janmaat and Marvin Zeegelaar heralded a switch to three at the back.

New signings Dodi Lukebakio and, much to everyone’s surprise because the pre-match belief was that he was still suspended, Didier Ndong were on the bench, alongside young defender Joy Mukena.

Antonio Conte also had his injury problems ahead of the game as Marcos Alonso joined Andreas Christensen and Ross Barkley in missing from the team which started the 3-0 humbling at the hands of Bournemouth at Stamford Bridge.

Their places were taken by Victor Moses, Willian and the previously out-of-favour David Luiz as the Blues boss also switched to a defensive trio, while January arrivals Olivier Giroud and Emerson Palmieri were among the replacements.

After much pre-match deliberating over potential formations, the Hornets started in a positive 3-4-3 with home debutant Deulofeu pushing up alongside Deeney and Richarlison in a forward trio.

And it was the home side who had the first attacking moments of note when after Janmaat swung over a cross from the right which Richarlison couldn’t get a clear header on, Zeegelaar returned the ball from the left side of the 18-yard box and Deeney saw his opening effort of the evening blocked.

The Hornets continued to look the more assured side in the opening stages and after another Janmaat cross from the right had been headed out, Doucoure brought the ball down but snatched a shot wide.

Next Deulofeu took on and beat Gary Cahill on his outside, only to hit the side netting after being played in by a good pass from Etienne Capoue.

The Hornets' start had been encouraging and they were to miss their best chance to date in the 10th minute when Deulofeu struck a deep corner over from the left and Deeney initially went near post, but spun off into space at the back, but he snatched his first time finish wide when he probably had time to take a touch.

Chelsea had barely been out of their half at all since the opening whistle but they did create a first opening when Moses’ cross from the right was chested down by Sebastian Prodl and the ball sat up for Willian, but he fired a first-time effort over the top.

The visitors did show signs of belatedly coming to life thereafter, albeit with minimal attacking effect before Bakayoko was rightly booked for a crude challenge on Capoue.

The Blues midfielder was then forced to hack over his own bar from another dangerous Deulofeu corner; this time with the delivery into the near post played flat and at pace.

Bakayoko’s contribution to the game had been less than auspicious and it was to get very much worse on the 30-minute mark when he took Richarlison’s leg and not the ball and referee Dean had no hesitation in reaching for his pocket, with the yellow card swiftly followed by a red.

Conte was always unlikely to continue with three forwards in the circumstances and so it proved four minutes later as Willian was the one to be sacrificed in favour of Cesc Fabregas.

Richarlison, who had been much more like the player of the first half of the season, was then to receive a pass from Doucuoure and attacked at pace on the inside before hitting a fine drive from 25 yards that was straight down Courtois’ throat.

The referee then took exception to something the Blues boss said and came over to the touchline to give him a lengthy lecture, much to the delight of most inside Vicarage Road.

But the moment Watford were to crave came three minutes before the interval when Janmaat slipped in Deulofeu in the inside right channel, Courtois dived for the ball, didn’t get it and was adjudged to have brought down the Barcelona loanee and again Dean was prompt in his actions, pointing to the spot.

Deeney duly did the rest, confidently beating the Chelsea keeper from 12 yards to deservedly give his side the lead by making it 1-0 before embarking on some rather exuberant celebrations.

Chelsea did have one chance to get back on terms before the interval when Pedro, who had been on the receiving end of a challenge for which Richarlison was booked in the 45th minute, worked some space on the left side of the area but fired over.

Prodl was also yellow carded early in the second half for a foul on Hazard, but there then followed a lengthy stoppage in play between Zeegelaar and Moses after they both went up to contest a far post header.

David Luiz was next to see yellow in the 59th minute for a cynical kick on Zeegelaar, but the Brazilian’s indiscretion almost received additional punishment when after the resultant free-kick had only been half cleared, Deulofeu curled a shot narrowly wide from the edge of the area.

Moments later the defender was in trouble again, dispossessed by Deeney which allowed Richarlison to latch onto the loose ball and his subsequent effort also wasn’t far wide of Courtois’ left-hand post with the keeper largely rooted to the spot.

Fabregas was the next player to see yellow for scything down Deulofeu but soon after Pedro had to be helped from the pitch with an injury which saw Giroud come on for his Blues debut.

Gracia made his first change in the 65th minute as Richarlison’s positive evening was ended as he made way for Pereyra, but that was to be followed by another Watford chance; Deeney heading back to Doucoure, who came bounding forward with the ball at his feet before hitting a piledriver which Courtois palmed away.

The Blues keeper had a more comfortable save to make from a well-struck long-range effort from Jose Holebas, before dropping to his left to hold a low curler from Pereyra after Janmaat had switched play from the opposite flank.

Orestis Karnezis had barely had a save worthy of mention but he was called into action with 10 minutes remaining, dropping sharply to his left to hold a Fabregas shot after Hazard had, for once, been able to find some space in the area.

And it was to be Chelsea’s Belgian wizard who was to come up with the fine equaliser with eight minutes remaining when he was not shut down as he received a pass from David Luiz and turned inside before curling a superb shot past Karnezis and into the far corner from 25 yards to level affairs.

What followed was remarkable and will go down in Hornets’ folklore.

The hosts almost went back in front when Capoue launched on a barracking run forward before slipping in Deulofeu, who mishit an effort wide on the stretch.

But if the Hornets were worried about not making the most of that opportunity, they needn’t have been because moments later Janmaat was dancing in off the right flank, played a give-and-go before jinking past another couple of challenges to score a stunning second.

But the Chelsea meltdown was only just beginning as moments later Deulofeu broke into the box and used Deeney as a decoy runner before firing emphatically past Courtois to make it 3-1 to net a thoroughly deserved first goal for the club.

The Belgian was replaced by Andre Carrillo after and the Peru international arrived in time to see Pereyra, incredibly, score a fourth with a blistering shot past Courtois into the far corner.

Vicarage Road was struggling to believe what it was witnessing as the champions were being dismantled and the Blues’ ignominy was to be completed when Karnezis denied Giroud a debut goal deep into six minutes of injury time with a fine save.

Watford: Karnezis; Mariappa, Prodl, Holebas; Janmaat, Doucoure, Capoue, Zeegelaar; Deulafeu (Carrillo 89), Deeney (Gray 90), Richarlison (Pereya 65). Subs not used: Bachmann, Ndong, Lukebakio, Mukena.

Chelsea: Courtois; Azpilicueta, David Luiz, Cahill; Moses, Bakayoko, Kante, Zappacosta; Willian (Fabregas 34), Hazard, Pedro (Giroud 64). Subs not used: Caballero, Rudiger, Fabregas, Drinkwater, Palmieri, Hudson-Odoi.

Bookings: Bakayoko for a foul on Capoue (25); Bakayoko for a foul on Richarlison – sent off (30); Richarlison for a foul on Pedro (45); Prodl for a foul on Hazard (50); David Luiz for a foul on Zeegelaar (59); Fabregas for a foul on Deulofeu (62).

Referee: Mike Dean.