The 29-year-old Belgian sustained what appeared to be a hamstring injury and was replaced on the hour mark at the Etihad Stadium in Wednesday's 2-0 Premier League win at home to Aston Villa.

"Kevin, like the doctor said today after reviewing the scan, will be 4-6 weeks out," Guardiola said before Saturday's FA Cup fourth-round tie at fourth-tier Cheltenham Town.

"It's a big blow, but we have to move forward.

"I'm not saying anything that anyone doesn't know, it is unfortunate for him and for us and we have to find a solution because everyone in their own life is struggling in the situation we are living and we have to adapt."

De Bruyne will now likely miss next month's game away to league champions Liverpool, their home game against fifth-placed Tottenham Hotspur and a trip to Mikel Arteta's Arsenal.

Guardiola said defender Kyle Walker, who went off in the first half against Villa after a collision with Jack Grealish, will miss Saturday's game.

"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 (away to West Bromwich Albion on Tuesday)," he said.

The Spaniard also said City's record scorer Sergio Aguero felt tired after testing positive for COVID-19.

"He felt uncomfortable in the first three days after testing positive. He felt quite tired, with all the symptoms you get," Guardiola said.

"Hopefully he can recover well and step by step return to the training sessions. We have missed our best striker for a long time but we have lived without him and we need to wait for them to come back as soon as possible."

Australian Associated Press