Manchester United midfielder Roy Keane is set to be sidelined for at least two weeks because of a hamstring problem.
The 34-year-old suffered a recurrence of the injury, which dogged him during pre-season, after coming on during Saturday's draw with Manchester City.
He is set to miss two Champions League games and the Premiership matches against Liverpool and Blackburn.
It is unclear if he will be fit for the Republic of Ireland's World Cup qualifier with Switzerland next month.
Alan Smith, who usually plays as a striker, may deputise for the midfielder as United attempt to find a long-term replacement for Keane.
Keane has become such a key player for the Old Trafford outfit over the years that whenever he is missing his absence has a huge impact.
In the 23 games in which Keane has not played over the last two seasons, United have dropped a total of 31 points - almost half of those available.