Sir Alex Ferguson praised the player while telling MUTV the problem is one that has followed Valencia for weeks. "He's had a bit of pain there for the last couple of weeks but he's been playing with it. That's the type of guy he is. He never mentioned it and plays on," Sir Alex said.
Valencia last played against Norwich on November 17. He missed the 1-0 Champions League loss to Galatasaray and Sunday's 3-1 Premier League victory away to Queens Park Rangers.
The 27-year-old Ecuadorian was named United's Player of the Year last season. At his best, he provides pace and power down the wing for Ferguson's side and proves dangerous with the ball at his feet or swinging in crosses.
Valencia has scored 16 goals for United since joining the club from Wigan prior to the 2009-10 season, but has failed to tally a single strike in 12 appearances this term.
He will miss Wednesday's home match against West Ham United.
The Hammers currently sit eighth on 19 points.
Manchester United sit atop the table having opened a one-point lead over crosstown rivals Manchester City.