Manchester United boss Sir Alex Ferguson expects striker Wayne Rooney to be out for around three weeks.

This was after the striker suffered a hamstring injury during Wednesday night's 1-0 Barclays Premier League win over Wigan.

Rooney put United ahead in the opening minute at Old Trafford but not long afterwards limped to the sidelines and was immediately replaced by Carlos Tevez.

"It is a hamstring injury," Ferguson confirmed.

"That will be about three weeks. We hope it is no longer."