Aston Villa came from behind to dramatically beat Brentford following a controversial red card for Bees defender Ben Mee.
Keane Lewis-Potter opened the scoring for the hosts at the end of the first half, shooting through a crowded penalty area after Villa failed to clear a corner from the left.
But the game turned when Mee was sent off in the 71st minute for diving in and catching Leon Bailey on the ankle.
On-pitch referee David Coote, close to where it happened, originally handed Mee a yellow card but, following a check by video assistant referee Craig Pawson, was advised to check the incident and it was then upgraded to a red card.
Brentford manager Thomas Frank was furious with the decision and got booked, with Villa capitalising on their player advantage six minutes later.
Bailey's cross was headed in at the back post by Alex Moreno for an equaliser, before Watkins headed in an 85th-minute winner from Boubacar Kamara's flick-on.
In a bad-tempered match, Kamara was then sent off for pushing the face of Yehor Yarmoliuk in stoppage time, with Villa boss Unai Emery also cautioned.
Follow live radio and text commentary of Sunday's Premier League matchesHow did you rate Brentford's performance? Have your say hereWhat did you make of Aston Villa's display? Send us your views hereUgly scenes could get both teams in trouble
Both sides could well face disciplinary action from the Football Association for failing to control their players in a few unpleasant incidents during the closing stages of the match.
Brentford and Aston Villa each had a player sent off, six players were booked for Brentford, four for Villa, and both managers were cautioned.
Watkins spent three years at Brentford between 2017 and 2020 and scored 49 goals for the Bees during that time.
However, he celebrated what proved to be the winning goal by standing inside the goal and pointing at a supporter, who may have been abusive towards the England striker.
Brentford's Saman Ghoddos then shoved Watkins, which caused the first of the scuffles with players from both sides getting involved.
After that came farcical scenes between Villa goalkeeper Emiliano Martinez and Brentford forward Neal Maupay.
Villa's Bailey nearly scored an own goal with a misjudged backpass from nearly the halfway line, with the ball hitting the side netting. Maupay, looking to get the ball for the corner, then ran into Martinez, who made a lot of what appeared to be minimal contact.
The pair were then involved in another incident, with this time Maupay over-reacting to little contact from the goalkeeper.
Martinez tried to forcefully lift Maupay off the ground and that sparked pushing from both sides' players with Kamara shoving the face of substitute Yarmoliuk and getting a red card.
Emery, who appeared to move Martinez away from the incident, was then cautioned in a fiery end to the encounter.
More to follow.
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Brentford
Squad number1Player nameFlekken
Squad number13Player nameM Jorgensen
Squad number5Player namePinnock
Squad number16Player nameMee
Squad number30Player nameRoerslev
Squad number24Player nameDamsgaard
Squad number6Player nameNørgaard
Squad number27Player nameJanelt
Squad number14Player nameGhoddos
Squad number23Player nameLewis-Potter
Squad number11Player nameWissa
Squad number7Player nameMaupay
Squad number15Player nameOnyeka
Squad number22Player nameCollins
Squad number33Player nameYarmoliuk
Squad number37Player nameOlakigbe
Aston Villa
Squad number1Player nameE Martínez
Squad number4Player nameKonsa
Squad number3Player nameDiego Carlos
Squad number14Player nameP Torres
Squad number2Player nameCash
Squad number7Player nameMcGinn
Squad number44Player nameKamara
Squad number41Player nameJ Ramsey
Squad number15Player nameÁlex Moreno
Squad number19Player nameDiaby
Squad number11Player nameWatkins
Squad number22Player nameZaniolo
Squad number24Player nameDurán
Squad number31Player nameBailey
Squad number32Player nameDendoncker
Line-ups
Brentford
Formation 3-5-2
1Flekken13M Jorgensen5Pinnock16MeeBooked at 71mins30RoerslevSubstituted forOlakigbeat 89'minutes24DamsgaardSubstituted forOnyekaat 68'minutesBooked at 90mins6NørgaardBooked at 46mins27JaneltBooked at 88minsSubstituted forYarmoliukat 88'minutesBooked at 90mins14GhoddosBooked at 86mins23Lewis-PotterSubstituted forMaupayat 68'minutesBooked at 90mins11WissaSubstituted forCollinsat 76'minutesSubstitutes
4Goode7Maupay15Onyeka21Strakosha22Collins25Peart-Harris26Baptiste33Yarmoliuk37OlakigbeAston Villa
Formation 3-5-2
1E MartínezBooked at 90mins4KonsaBooked at 86mins3Diego Carlos14P TorresSubstituted forZanioloat 81'minutes2CashSubstituted forBaileyat 65'minutesBooked at 80mins7McGinn44KamaraBooked at 90mins41J RamseySubstituted forDendonckerat 90'minutes15Moreno19DiabySubstituted forDuránat 65'minutesBooked at 87mins11WatkinsSubstitutes
16Chambers17Lenglet22Zaniolo24Durán31Bailey32Dendoncker42Marschall47Iroegbunam78ProctorReferee:David Coote
Attendance:17,034
Live Text
Match ends, Brentford 1, Aston Villa 2.
Second Half ends, Brentford 1, Aston Villa 2.
Offside, Brentford. Nathan Collins is caught offside.
Jhon Durán (Aston Villa) wins a free kick on the right wing.
Foul by Ethan Pinnock (Brentford).
Nicolò Zaniolo (Aston Villa) wins a free kick in the defensive half.
Foul by Michael Olakigbe (Brentford).
Yehor Yarmoliuk (Brentford) is shown the yellow card.
Emiliano Martínez (Aston Villa) is shown the yellow card.
Boubacar Kamara (Aston Villa) is shown the red card for violent conduct.
Nicolò Zaniolo (Aston Villa) wins a free kick in the defensive half.
Foul by Michael Olakigbe (Brentford).
Attempt missed. Ezri Konsa (Aston Villa) right footed shot from outside the box is close, but misses to the right. Assisted by John McGinn.
Corner, Brentford. Conceded by Álex Moreno.
Neal Maupay (Brentford) is shown the yellow card.
Corner, Brentford. Conceded by Leon Bailey.
Frank Onyeka (Brentford) is shown the yellow card for a bad foul.
Nicolò Zaniolo (Aston Villa) wins a free kick on the left wing.
Foul by Frank Onyeka (Brentford).
Substitution, Aston Villa. Leander Dendoncker replaces Jacob Ramsey.