Unai Emery vows to tackle indiscipline after Boubacar Kamara sending off against Brentford
Keane Lewis-Potter opened the scoring for the home side on the stroke of half-time but the game changed when Brentford defender Ben Mee was sent off about 20 minutes from time after flying into Leon Bailey.
Alex Moreno levelled in the 77th minute, with Ollie Watkins completing the turnaround eight minutes later.
Watkins' celebration in front of his old fans caused an on-pitch stir, with the referee brandishing yellow cards to Ezri Konsa and Saman Ghoddos.
Villa midfielder Boubacar Kamara was shown a red card deep into stoppage time for violent conduct.
Emery said he would take action to tackle the indiscipline.
"At the end some moments, some behaviour, of us as well, I'm going to manage our behaviour and take control of it," he told the BBC. "I will analyse it with our players because it was not normal.
"We were a bit excited and we needed control of ourselves. When you are reacting like that, other players and the other opponent is maybe not being in good behaviour like the match needed.
"I'm going to manage everything we did that was not good and our mistakes in our behaviour.
"Maybe it's not the best for football and for us but always we have very good behaviour with the referees, always respect their decisions, VAR and I will keep doing the same."
