London  - An injury to Wayne Rooney marred a good night for Manchester United as they moved to within two points of leaders Liverpool in the English Premier League after beating Wigan Athletic 1-0 at Old Trafford on Wednesday.

England striker Rooney scored the only goal of the game in the first minute of the match to lift champions United above Chelsea into second, but the striker is now expected to be out for three weeks with hamstring trouble.

Victory at Bolton Wanderers on Saturday would see United go top, with Liverpool playing Everton in the Merseyside derby on Monday night.

Rooney gave United the dream start inside a minute when he got on the end of a cross from World Player of the Year Cristiano Ronaldo.

Rooney went off soon after and Wigan matched United thereafter, though Carlos Tevez should have done better after rounding Chris Kirkland only to lose control.

"It is a hamstring injury," United manager Sir Alex Ferguson confirmed, of Rooney's problem. "That will be about three weeks. We hope it is no longer."

Ferguson, who watched his side complete their ninth consecutive clean sheet, was full of praise for Wigan.

"Wigan are the best side that has played here this season by far," he said. "It was an outstanding performance from them. They really made us work. They are a very positive team." (dpa)