Arsenal defender Per Mertesacker appears certain to miss the rest of the season after undergoing ligament surgery.
Mertesacker suffered an ankle injury during the club's 2-1 victory over Sunderland last weekend and it has now been confirmed that he faces a lengthy spell on the sidelines.
Arsene Wenger, speaking ahead of the club's FA Cup clash with Sunderland, said: "Unfortunately he has had surgery and we have lost him for a while. How long I don't know. He had reconstruction of his ligaments, so it will be long term."
There was better news on Laurent Koscielny, who sustained a knee injury during the 4-0 defeat to AC Milan.
"He had a scan yesterday and the news is quite good," Wenger said. "He will be out for hopefully around a week. He will miss the Sunderland game, but he should be back for next week."
Wenger also revealed that Gervinho, having returned from African Nations Cup duty, will be available for the weekend, and that Carl Jenkinson will be back in training on Monday.