Pep Guardiola has admitted that Manchester City can no longer 'count on' on captain Vincent Kompany after he picked up another injury in Sunday's 2-1 win over Manchester United.
The Belgian defender was forced to withdraw at half-time at Old Trafford, although the extent of the injury is not yet clear.
City secured victory without Kompany, but the latest knock will be a significant setback for both player and club.
Speaking to Sky Sports after the game, Guardiola said: “Kompany is injured. We wait and see. Vinny is always like this – unfortunately we can’t count on him for a long time.”
The 31-year-old, who has been hampered by almost incessant injury problems, was replaced by Ilkay Gundogan and Fernandinho moved into defence.
Eliaquim Mangala was later introduced to play alongside Nicolas Otamendi, currently City's only fit centre-backs.
But Guardiola's side were able to cope without the absentees, leaving Old Trafford with a win thanks to goals from David Silva and Otamendi.
"Amazing, we played outstanding," Guardiola added. "We play here, Old Trafford, to try to be patient in the right moment, it was so, so clever. We controlled the counter-attack, the long balls.
"We are so happy, it's such an important game for us, of course, and our rivals here at Old Trafford, playing the way we played, it's a big credit to our players.
"Definitely we [should have won by more]. That can happen, but the personality to play here is what I want. I am happy because with this kind of play we can do it in England, that's why I'm so happy, because people say the way we played in Barcelona, it is not possible in England. It is possible. We did it."