Pep Guardiola said Manchester City will be without injured Belgium winger Jeremy Doku until the new year.
Doku suffered a leg problem last week and was absent from City's 3-0 win at Crystal Palace.
Speaking ahead of Wednesday's League Cup quarterfinal against Brentford, City boss Guardiola said the influential Doku will not be back in action for up to three weeks.
Asked when he is likely to return, Guardiola said: "Jeremy (will be out) two or three weeks. New year at Sunderland maybe."
Doku's absence is a major blow to Guardiola in the midst of his most consistent season with City since arriving from French club Rennes in 2023.
The 23-year-old has scored three goals and provided five assists, with his dynamic play on the flanks helping City striker Erling Haaland enjoy another prolific campaign.
As well as missing Brentford's visit to the Etihad Stadium, Doku will be sidelined for Premier League games against West Ham on December 20 and Nottingham Forest on December 27.
City's trip to face Sunderland at the Stadium of Light on January 1 is the earliest Doku will be back.
Brazilian winger Savinho is likely to be given the chance to deputise for Doku after losing his place in recent weeks.
He came off the bench to win a penalty against Palace, but impressed Guardiola was more with his work rate.
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"He lost one or two balls and in two seconds he was a full-back," Guardiola said.
"I was incredibly pleased. Two actions where he lost the ball he was a machine. He doesn't like to listen, but I had to tell him.
"You come from the bench, you have to run double because the other guys are tired. Savinho is going to play a lot of minutes."
Trailing leaders Arsenal by just two points in a tense title race, second-placed City cannot afford more injuries heading into the hectic Christmas period.
With that in mind, Guardiola will make changes for the Brentford clash, which comes just 72 hours after the hard-fought win over Palace.
"We have some injuries, like John (Stones) and Jeremy. We will see. It's one step to get to the semifinals," he said.
"Now we have less recovery. The players that didn't play recently are going to play.
"Some from the academy will play, because then we play West Ham. I'm not saying it's not a priority getting to the League Cup semifinals, but normally when we achieve it it's when we have no injuries and we can rotate the team."