Manchester City manager Manuel Pellegrini fears that star striker Sergio Aguero could be out for up to eight weeks with a calf injury.
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However, the outcome of the injury could be much more serious, with the Premier League’s second top scorer a chance to miss the glamour Champions League tie with Bayern Munich.
“I am not a doctor. It is very difficult,” Pellegrini said after the 3-1 over Leicester in the Capital One Cup. “The doctor has said he has at least one month or eight weeks. We will see.
“I don't how many weeks but it will be at least one month. It is very difficult to know at this moment how many weeks it can be.”
And City’s injury list could add another long-term casualty with defender Pablo Zabaleta lasting only 11 minutes in the club’s quarter-final victory over Leicester City.
The Argentina international was replaced by Dedryck Boyata after suffering what looked to be a hamstring injury.
Manchester City tweeted that they would reveal the extent of the 28-year-old’s injury as soon as possible.
On the match against Leicester, Pellegrini said it was a “professional performance” by his side and looked forward to a dream semi-final against possibly bitter rivals Manchester United.
"We knew it was not going to be an easy game because Leicester are a very good team, they were playing at home and were motivated,” Pellegrini said.
“The team played very well, especially in the first half. Maybe when the score was 3-0 we stopped a little bit in our pace.
“Leicester had possession of the ball in the last minutes but I think it was a professional performance in all senses.
"It is an important competition, it is important to win every game you play in and to get to the final at Wembley would be wonderful for the supporters.
“We could have Tottenham and Manchester United also in the semi-final so that would be beautiful for the fans."
And the Chilean picked out striker Edin Dzeko for praise, adding: "I have always said Edin Dzeko is a very important player.
“He hasn't been playing normally in the 11 starting because [Alvaro] Negredo and Aguero are playing well, but every time he has played he has played very well."
Information from the Press Association was used in this report.