Wenger: Costa Should Have Gone  (Sky Sports)

Arsenal manager Arsene Wenger criticised referee Mike Dean after he failed to send off Chelsea striker Diego Costa, but red-carded two Arsenal players in a bad-tempered London derby.

Arsenal lost 2-0 at Stamford Bridge but it was Costa's tangling with the Gunners' defence that most offended the manager.

Television replays showed the intimidating Brazil-born Spaniard pushing Laurent Koscielny in the face during tussles in the Arsenal penalty area in the first half and he was then involved in a series of altercations with Gabriel who was sent off just before half-time.

"He can do what he wants, he stays on and everybody else who responds to him has to be sent off. I think it is unacceptable his behaviour," said Wenger.

"If you look well at the pictures what he does to Koscielny before he pushes him down he hits him in the face and the throat, he always gets away with it.

"It is surprising and I don't understand Mike Dean's decision at all, not on the sending-off - why does Diego Costa stay on the pitch and Gabriel sent off?

Wenger conceded that Gabriel deserved his red card for kicking Costa in a melee of protesting players at the end of the first half.

"Gabriel is guilty for getting involved of course he should not have reacted at all," he said.

"We expected that kind of game. We were not surprised but I expect the referee to make the right decision."

Asked if he felt retrospective action from the Football Association was called for, Wenger replied: "That is the least they could do, but he will do the same again next week and the week after and he always gets away with it.

"For me, it is always in provocation and he uses well the naivety of Mike Dean today.

"Look at the pictures, it tells you a lot on slow motion. Before the cross comes in he hits him.

"The fact is surprising that Diego Costa got away with what he did, that we go into half-time with a red card and he stays on the pitch.

"They [referees] are professional people, and they have to make the right decision."

Wenger also suggested the foul that led to Chelsea's first goal, headed home from a free kick by centre back Kurt Zouma in the 53rd minute should not have been given. "It was hardly a touch," he said.

Arsenal's woes were compounded when Santi Cazorla was sent off after a second yellow card in the 79th minute leaving Arsenal vulnerable to Eden Hazard's stoppage-time strike that took a deflection off Arsenal substitute Calum Chambers wrong-footing former Chelsea 'keeper Petr Cech, playing for the opposition for the first time after his 11-year career at Chelsea.

There is no love lost between Wenger and his Chelsea counterpart Jose Mourinho, who, as if in retaliation said he felt Costa was man of the match.

The managers set the tone of the encounter by shaking hands while barely looking at each other at the start and Wenger disappeared quickly down the tunnel at the whistle without acknowledging the Portuguese.

Wenger's Arsenal have failed to beat a Chelsea team managed by Mourinho in the Premier League in 11 games between the pair.

That statistic rankles but Wenger's sides have also suffered from sendings off for petulance.

Striker Olivier Giroud earned two yellow cards for dissent and a bad tackle on Wednesday during Arsenal's 2-1 defeat by Dynamo Zagreb in the Champions League.