ARSENAL have been hit with a major injury blow ahead of Sunday’s derby visit of table-topping Chelsea with the news that William Gallas is still struggling with a swollen eye.<br /><br />The French defender suffered a nasty clash of heads with team-mate Andrey Arshavin during Tuesday night’s 2-0 Champions League victory over Standard Liege, before eventually limping off with an ankle injury.<br /><br />But Gallas’ eye is still so swollen he can not even put his contact lenses in and boss Arsene Wenger admits the key defender remains a “big question mark” for the crunch Premier League clash against his former club.<br /><br />“Today I cannot say that William Gallas will play, unfortunately,” Wenger said. “The ankle should be alright but the eye is still very, very swollen. He wears contact lenses and at the moment he would not get them in. <br /><br />“We hope on Sunday it will be better. He is not comfortable but I am optimistic because we still have three days. It is Thursday today and we play on Sunday afternoon so we are confident he can make it. <br /><br />Of forward Arshavin, Wenger added: “Arshavin is okay, he was in shock, but he is okay.”<br /><br />The Liege game has already come at a cost for the Gunners with full-back Kieran Gibbs fracturing a foot bone in the dying minutes, keeping him out for around three months.<br /><br />Losing Gallas would be a huge blow for the Gunners as they look a tame a potent Chelsea strikeforce which welcomed back Didier Drogba from injury in Porto on Wednesday night.<br /><br />Blues boss Carlo Ancelotti will also be boosted by the successful returns of midfielder Michael Ballack on Wednesday, although Frank Lampard is still out with a thigh injury.