Manchester City striker Sergio Aguero is a doubt for the Premier League clash with rivals Manchester United due to injury.
Aguero was taken off at half-time in Wednesday's UEFA Champions League defeat to Barcelona with a hamstring problem, leading to fears the Argentina international could miss a large part of City's run-in.
While manager Manuel Pellegrini said Aguero's injury was not "very serious", he confirmed the 25-year-old will be out for more than a week, meaning he could miss the Manchester derby on March 25.
"Tomorrow, we will know the extent of Sergio Aguero’s injury. We do not know exactly what is wrong," Pellegrini said on Friday.
"Aguero will be out for more than one week but I don’t think it is very serious.
"Matija Nastasic and Stevan Jovetic are still recovering. Maybe next week they will be fit. Micah Richards also has a problem."
Aguero has been hampered by a number of injuries this season, but still boasts 26 goals from 28 games in all competitions.