Manchester City full-back Pablo Zabaleta is set to be out for up to a month with a knee injury.
Manuel Pellegrini's side have made an impressive start to the season, beating West Brom and Premier League champions Chelsea 3-0.
But they will now have to cope without the Argentina international, who has yet to make an appearance this season, after he suffered a setback in training.
Zabaleta told City's official website: "It happened in training. It's the first time in 12 years of senior football that I've ever been injured like this so it's a blow, especially at the start of the season."
The injury means Bacary Sagna is City's only fit recognised right-back ahead of Sunday's trip to Goodison Park to face Everton.
Pellegrini's men have received better news regarding Fabian Delph and Gael Clichy, with both players returning to training following injuries.
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