Wayne Rooney sustained minor ankle ligament damage and did not break a bone during Manchester United's Champions League loss at Bayern Munich.
While Rooney will miss United's match against Chelsea on Saturday, the Premier League leaders didn't project a timeframe for Rooney's return to action.
Rooney, who has 34 goals for the Red Devils this season, hurt his right ankle in the final minute of Tuesday's 2-1 loss in the first leg.
"We're pleased to report that Wayne has not suffered a fracture. The scan revealed only minor ligament damage," United said on its web site Thursday. "For now, the club is not commenting on how many games Wayne is likely to miss."
Manager Alex Ferguson will provide an update at his weekly Friday news conference.
Rooney is a key player for England. preparing for its World Cup opener against the United States on June 12.
Seeking its fourth straight Premier League title, Manchester United (23-6-3) has 72 points, one ahead of second-place Chelsea (22-5-5) and four in front of third-place Arsenal (21-6-5) with six league games remaining.
With Michael Owen also out injured, Ferguson is likely to start Dimitar Berbatov at forward in Saturday's game against Chelsea at Old Trafford.
"Everyone knows how Wayne Rooney is important for this team," Blues manager Carlo Ancelotti said. "He has had a fantastic season but his injury could be an advantage for us."