Arsenal boss Arsene Wenger confirmed a serious knee injury for Francis Coquelin after victory over Chelsea.

The only blemish on their fourth consecutive league victory was that Coquelin went off with a knee injury in the first half.

Coquelin was out for 10 weeks with a knee problem last season and Wenger confirmed it appears to be a similar issue.

"He has a knee injury at the same place he had last year at West Brom," Wenger said.

"That's the negative of the day. We don't know if the damage is as big at the moment, we have to wait for 48 hours. But he left the stadium in a brace and I'm a bit worried for that."