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The 25-year-old was reintroduced to City's starting XI on Saturday in their 3-2 defeat to Norwich and came under heavy criticism for a defensive error which led to the gamewinning goal at Carrow Road.
But now the England international faces a lengthy spell on the sidelines, with City now down to just one fit centre-back - Nicolas Otamendi - heading into their Champions League opener against Shakhtar Donetsk on Wednesday evening.
Guardiola admits he faces a significant task now he is down to just one fit centre back.
"As a manager it’s an incredible challenge, just one central defender in Nico," Guardiola said.
"I believe. People don’t know the spirit and resolve to solve this problem. The players going to come back with [Fernan]Dinho, Garcia, Harwood-Bellis...
It’s happened, but what we are not going to do is complain. If they are not able, they are not able. We have to have 11 players on the pitch and I like it, to find a solution.
Guardiola will also be without Phil Foden for their Group C clash against the Ukrainian champions due to a stomach problem.