Manchester City are waiting to discover the extent of the latest injury suffered by captain Vincent Kompany after he limped off on 11 minutes in their win at Newcastle on Wednesday.
"I don't know what is going to happen," said boss Pep Guardiola. "Unfortunately he is injured again."
The 31-year-old had returned from his latest injury in the 4-0 win over Bournemouth on 23 December.
The Belgium defender had been replaced in the Manchester derby on 10 December.
And after that match Guardiola had said: "Unfortunately we can't count on him for a long time."
Kompany, who has been at the club since 2008, had been injured earlier in the season while on international duty.
And his brief outing against Newcastle was just his 10th appearance of the season.
The injury happened on the same day that Liverpool agreed a £75m deal with Southampton to sign defender Virgil van Dijk - a player who had been linked with City.