Arsenal expect captain William Gallas to be sidelined for three weeks with the groin injury he suffered at Blackburn.

The defender went down in agony off after hurdling a 24th-minute challenge from Roque Santa Cruz in yesterday's 1-1 Barclays Premier League draw.

He immediately called for assistance from the bench and, a few minutes later, hobbled off to be replaced by Philippe Senderos.

"He has done his groin, I knew it straight away," manager Arsene Wenger said on the club's official website, www.arsenal.com. "He will be out for three weeks."