Gallas, who has started alongside Thomas Vermaelen in every one of Arsenal's Premier League and Champions League matches so far this season, suffered the injury in a clash of heads with his team-mate Andrey Arshavin during the Champions League victory over Standard Liege on Tuesday night.

Arshavin suffered a gash to the top of his head but was able to play on, while Gallas, having also taken a knock to an ankle, was forced off.

Wenger says that Gallas' ankle injury is not a concern - but his eye remains so swollen he cannot get his contact lens in.

"I cannot say that William Gallas will play, unfortunately," said Wenger.

"The ankle should be all right but the eye is still very, very swollen.

"He is not comfortable but I am optimistic because we still have three days. Arshavin was shocked but he is OK."

If Gallas is ruled out, Wenger has the option of moving Alex Song from midfield into central defence, or he could play Mikael Silvestre - who might be preferred at left-back - or Philippe Senderos alongside Vermaelen.