Arsene Wenger insists Diego Costa "should have been sent off twice" during Chelsea's victory over Arsenal on Saturday.
Jose Mourinho's men secured only their second win in the Premier League this season following second-half goals from Kurt Zouma and Eden Hazard, while the Gunners ended the match with nine men after Gabriel Paulista and Santi Cazorla were sent off.
Gabriel was sent off for kicking out at Costa, but television replays have shown the Chelsea striker slapping the face of Laurent Koscielny in the build-up to his lengthy altercation with the Arsenal centre-backs.
Asked by BT Sport if he felt a sense of injustice, Wenger replied: A big one, yes. Because I think Diego costa should've had a red card, I wouldn’t like to be Mike Dean tonight.
"I cannot understand this situation. Costa, twice should have been sent off.
"Look at the situation before the cross comes in. He hits Koscielny in the face on purpose. He makes a fuss of it and in every game he is aggressive and gets away with it because of the weakness of the referee.
"I think two sendings off for us and Costa staying on the pitch is a shame."
Wenger did admit, however, that Gabriel deserved to be sent off, adding: "Gabriel deserves a red card and I agree, but you expect the referee to make the right decisions. That’s all you want."
The two managers failed to shake hands at the end of the game, but the Frenchman played down any suggestion he'd deliberately avoided his opposite number by claiming "he's always available".
The 65-year-old also revealed midfielder Francis Coquelin picked up an injury and will definitely miss his side's next match against Tottenham in the League Cup on Wednesday.