Arsenal fear Theo Walcott will be out for four weeks with the knee injury that forced him off in Saturday's 2-0 home win over Tottenham Hotspur in the FA Cup. Walcott will undergo a scan on Monday but the early indications are that he strained ligaments after the 81st-minute challenge with the Tottenham full-back Danny Rose.

Walcott has already missed a little over two months of the season because of an abdominal problem that required surgery. He returned on 23 November as a substitute against Southampton and he recovered his place in the starting XI on 14 December at Manchester City. He has five goals in six starts but now faces further disruption.

Arsène Wenger also lost Thomas Vermaelen and Mikel Arteta to injuries against Tottenham. The manager said he hoped Vermaelen had not suffered knee ligament damage. Arteta took a heavy kick to a calf in the first half and was withdrawn in the 75th minute. Both players will be assessed on Monday.

Walcott was abused by a section of the travelling support as he was taken off on a stretcher and he responded by making a two-nil scoreline gesture with his hands. Coins and other projectiles were thrown at him but, as Walcott's gesture was not offensive, he is unlikely to face censure from the Football Association. The governing body will investigate the conduct of the Tottenham fans.