Gündogan limped off in tears after sustaining the injury in Wednesday's 2-0 Premier League victory at home to Watford.

It was a bitter blow for the 26-year-old, who spent the close season recovering from a dislocated knee that ruled him out of Euro 2016.

Guardiola told a news conference: "It's so, so difficult for him, it's sad for him, we're going to miss him a lot. It's unlucky, but that's football.

"Now we need him to feel we are there and wait and come back safe. He’s going to be operated (on) and be back as soon as possible."

Gündogan joined City from Borussia Dortmund in June for a fee of €27m ($28m). He has made 16 appearances, scoring five goals, including doubles against West Bromwich Albion and Barcelona.

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