Mauricio Pochettino admitted his Chelsea side need to grow up after they slumped to a third league defeat of the season.
Malo Gusto picked up an avoidable red card after a tackle on Lucas Digne on the halfway line and will now be banned for three games.
Striker Nicolas Jackson will also serve a one-game ban after being shown his fifth yellow card of the campaign already, just six league games in.
Villa took full advantage of Chelsea being down to 10 men when Ollie Watkins ran through to score the second-half winner for Unai Emery’s side.