Pep Guardiola revealed Benjamin Mendy will miss up to three months with another knee injury.
Mendy underwent surgery in Barcelona with Dr Ramon Cugat last week and stayed in Spain until Thursday for continued rehabilitation.
The left back suffered a meniscus problem after the 3-1 victory over Manchester United before the international break.
That is not a repeat of the cruciate knee ligament injury that saw him miss the majority of last season but Mendy is still set for a significant spell on the sidelines.
’It’ll be 10-12 weeks,’ Guardiola – who also confirmed Bernardo Silva is not fit – said before Saturday’s game against West Ham.
City will not enter the January market to find a replacement for Mendy, although his repeated injury issues are a concern.
Guardiola also heaped praise on former City manager Manuel Pellegrini, who will face his old employers for the first time at the London Stadium.
Pellegrini deployed an attractive style of play at the Etihad Stadium and Guardiola added: ‘When you are a blind guy you recognise his style.
‘At Villarreal he was incredible. A small city, the way they played and owned a style was impressive. He made 96 points at Real Madrid and then won the league here.
‘He helped this club to be where we are right now. He’ll do well at West Ham, where there are many good supporters.’