Wayne Rooney scored the winner but suffered a hamstring injury in a 1-0 victory over Wigan Athletic that moved Manchester United up to second in the Premier League on Wednesday.
The England striker netted after just 54 seconds at Old Trafford but hobbled off soon after scoring and will be sidelined for at least three weeks,manager Alex Ferguson said.
Unfortunately we lost Wayne Rooney and Carlos Tevez came on and did fantastically for us before he got injured as well. It was a test of our character for the last half hour because it was an absolutely brilliant performance by Wigan, said Ferguson.
United,who have 44 points and a game in hand,will go top if they beat Bolton Wanderers on Saturday as leaders Liverpool,who have 46,do not play until they host Everton in the Merseyside derby on Monday.
Rooneys first-minute strike came after a good run and cross from newly-crowned FIFA World Player of the Year Cristiano Ronaldo,although that was virtually Rooneys last contribution as he limped off eight minutes later.
He was replaced by Carlos Tevez.
Wigan battled hard but failed to score against a United side who have now gone nine Premier League games without conceding a goal.