Kevin De Bruyne will be out for four to six weeks due to a hamstring injury, Manchester City boss Pep Guardiola says.
De Bruyne, who was injured in Wednesday's 2-0 home win over Aston Villa, is set to miss City's key Premier League fixtures against Liverpool, Tottenham and, in all likelihood, Arsenal next month.
Guardiola also confirmed that Kyle Walker would miss Saturday's FA Cup fourth-round tie at League Two Cheltenham after picking up a problem in Wednesday's league win.
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"Kyle had a big impact kick in his hips, but just a kick, so is not available tomorrow but we wish he is available for the next game," said the City boss.
"Kevin, the doctor had to review the scan this morning, and he will be out between four and six weeks."
If De Bruyne's recovery takes the full six weeks, he will miss at least nine matches for City, including their Champions League last-16 first leg against German side Borussia Monchengladbach.
The Belgian international would be pushing to return for the Manchester derby on March 6, according to that recovery timeline.
City are second in the league, two points behind rivals Manchester United with a game in hand.
"We have to move forward," said Guardiola. "I'm not saying that nobody doesn't know about his importance.
"Unfortunately for him and us, he'll be out for an important part of the season, and we have to find a solution because everyone's struggling in this situation, and we have to adapt.
"The players don't want to get injured, but they are human. Why in the FA Cup can we use five subs but in the league not? It is a different competition. Is it a special one? It's not just because it's Kevin. It is everyone for the past five seasons. It is too many games."
'We have missed our best striker'
Guardiola also said he hopes "our best striker" Sergio Aguero can return to full fitness soon after the Argentina international revealed he tested positive for coronavirus earlier this week.
After a close contact, I've been self-isolating and the latest test I took was positive for COVID 19. I had some symptoms and I'm following doctor's orders for recovery. Take care, everyone!— Sergio Kun Aguero (@aguerosergiokun) January 21, 2021
It is another setback for Aguero who has started just three games for City this season due to struggles with injury.
Guardiola knows just how much City have missed their record-scorer and wants the 32-year-old back as soon as possible.
"What we wish right now is that Sergio feels better," said Guardiola.
"He felt uncomfortable in the first three days after testing positive. He felt quite tired, with all the symptoms you get. Hopefully he can come back. Step by step in training. A long time we have missed our best striker."
Aguero had been self-isolating after being identified as a close contact of another confirmed case.
But the 32-year-old revealed he had now too tested positive, confirming it on his Twitter.
He wrote: "After a close contact, I've been self-isolating and the latest test I took was positive for Covid-19.
"I had some symptoms and I'm following doctor's orders for recovery. Take care, everyone!"