Pep Guardiola has confirmed forward Leroy Sane could be out for "six or seven months" with an ACL injury.
The club confirmed on Thursday that Sane was due to have surgery for the injury suffered in City's Community Shield win over Liverpool at Wembley Stadium last Sunday.
On Friday, Guardiola expanded on the extent of the damage, saying: "I'm not a doctor or physio but normally this kind of injury, ACL, is six/seven months.
"Hopefully in February/March, he can come back with us."
Despite Bayern Munich's strong pursuit of Sane in the transfer window, Guardiola confirmed the 23-year-old was firmly in his plans for the upcoming season.
"I didn't potentially think about him leaving," Guardiola said.
"I always said the same: he's our player, he didn't tell me: 'I want to leave' so I always thought he was our player. For that reason, he played all the pre-season in the starting XI, in the final, he played.
"So, unfortunately, it is incredibly bad news because in three seasons we had three ACLs [Ilkay Gundogan and Benjamin Mendy have previously suffered the same injury].
"He's a young player and hopefully he will recover well. He is in the best hands possible in terms of the situation (surgery) next week.
"All the people here are going to try and help him be comfortable in the tough moments because after one month, two months he will feel alone. We will try to be with him as much as possible and help him recover as well as possible."
Last season without left-back Mendy, City used makeshift players to cover for him, and Guardiola said City are similarly not prepared to plug in a like-for-like replacement for Sane.
"Without him? We don't have an alternative," he said.
"In the first season, we didn't have Gundogan. The second season with Benjamin, we played with Fabian Delph and Oleksandr Zinchenko when both are not left-backs.
"They did it incredibly well and now with Leroy, we will just let him know we are here and we will wait for him."
Guardiola, meanwhile, says Man City players have voted David Silva as their new club captain.
Ahead of City's first Premier League game of the season - they face West Ham on Saturday at 12.30pm - Guardiola said: "David Silva will be our club captain, then Fernandinho, Kevin [De Bruyne] and Sergio [Aguero]."
Silva, now 33 and entering his 10th season with City - has made 284 appearances for the club, scoring 54 goals and helping guide them to four Premier League titles, two FA Cups, and four League Cups.
Vincent Kompany had been the club captain since the 2011/12 season, but after his departure this summer to become player-manager of Anderlecht, Guardiola allowed the players to choose the next player in line.
When asked what attributes Silva has and why he was chosen by the players, Guardiola said: "The captain has to be what he is.
"David has almost one decade here with the club, in the Premier League. He is incredible, he has the respect of his team-mates.
"[To be a good captain], he has to be himself. There will be no problems.
"Normally, the captain is the life of the locker room - they know each other; they have fun a lot when they are together.
"There will be no problem. He will be a good captain."
Man City team-mates send Sane well wishes
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