Ruben Dias is set to miss Sunday's Manchester derby and be sidelined for up to six weeks with a hamstring injury.
The Manchester City defender was forced off with the issue at half time of Tuesday's 2-0 FA Cup fifth round win over Peterborough.
Pep Guardiola confirmed on Friday that Dias will miss at least a month at a critical stage of the season.
"Muscular, hamstring. Four to six weeks. It happens," the City manager said.
"In other seasons, our best players have been out for months. I'd love him [to play] but he's not there, I will not cry.
"It is what it is. We have decent players available. We have 14-15 players. With these players we are going to fight and try to play good. We play with our people and hopefully our people support as they always do."
Nathan Ake will also miss Sunday's derby after also coming off injured at London Road on Tuesday evening.
If Dias is sidelined for a full six weeks, he could miss the top-of-the-table clash with title rivals Liverpool at the Etihad on 10 April.
The Portugal international would also be likely to sit out of the Champions League quarter-finals, with the two legs to be played from 5-6 and 12-13 April.
City take a 5-0 lead into their return leg against Sporting Clube de Portugal at the Etihad in next week's round of 16.
