Arsenal boss Arsene Wenger blasted Joey Barton after seeing his side squander a four-goal lead at Newcastle and leave with only a point.
After midfielder Abou Diaby had been sent off three minutes after the restart for pushing Barton to the ground following a rugged challenge, they crumbled and shipped four goals inside 19 bewildering minutes, the last of them Cheik Tiote's stunning 87th-minute equaliser.
Wenger, who was also critical of the two penalties awarded by referee Phil Dowd, said: "It was a completely unnecessary sending-off, and I believe Barton was very lucky to stay on the pitch for the tackle on Diaby."
He added: "It's a shame [for Diaby] because he had a great first half. Sometimes you could understand when he has a bad game, but he had an outstanding game.
"I explain that by the fact that he has been injured so many times from bad tackles that he lost a bit quickly his nerves because this boy has been out for a long time and many times. Certainly the tackle provoked his reaction."
Newcastle manager Alan Pardew was quick to defend Barton, whose England claims he promoted once again.
Pardew said: "You have got to make a challenge. It was a proper, honest challenge - I have seen it two or three times and there's nothing wrong with it.
"He goes for the ball, he wins the ball clean. He is aggressive in the challenge, he takes a little bit of the player after he has won the ball."
Wenger admitted the psychological damage inflicted by Newcastle's fightback could have a lasting effect.
Asked about the cost, Wenger said: "Mathematically, two points; psychologically, the damage is a bit bigger because everybody is, of course, very, very disappointed in the dressing room. But only the future will tell."
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