Jack Grealish is facing a month out of action after sustaining an injury in training, putting his participation in the Champions League last 16 clash with Sporting CP and the Manchester derby at risk.
The Manchester City forward missed his side's 4-0 victory over Norwich on Saturday, during which Raheem Sterling scored a hat trick and Phil Foden grabbed the other goal.
Speaking before that game, City manager Pep Guardiola revealed he hoped the former Aston Villa star would be available sooner rather than later.
He said: "Jack Grealish is injured. He has the same problem that he had last season with Villa.
"He trained after the game against Brentford, we did a test but he was not ready today, but hopefully [he will be ready] next Tuesday.
"All my career, when you play three days later, I don't like to play all the same players.
"When you play three days ago and you play three days later, I don't like to play with less recovery time and the players who play have my full confidence."
City face Sporting on Tuesday, with the return leg set for March 9, three days after the Manchester derby against Man Utd.
While the Citizens will want Grealish back and available for those games, they haven't suffered in his absence. Saturday's win at Carrow Road took them 12 points clear at the top of the Premier League table as they look to retain the title they won last season.
Grealish struggled with a shin problem last term which ruled him out of 12 matches for Villa, though he was fit enough to feature at Euro 2020 with England.