Arsene Wenger: "It was a completely unnecessary sending-off, and I believe Barton was very lucky to stay on the pitch for the tackle on Diaby.
"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."