Manchester City's England midfielder James Milner has been ruled out of this weekend's Barclays Premier League clash with Everton.
Milner limped off with a hamstring injury soon after scoring City's second goal in their 2-0 midweek win at Wigan.
The 26-year-old could also be doubtful for next week's Champions League trip to Borussia Dortmund and the derby with Manchester United which follows, but City are not yet sure of the seriousness of the problem.
Manager Roberto Mancini said: "James is out for tomorrow. We will try to recover him for next Sunday but we don't know."
Milner had been making only his second appearance since returning from a lay-off with a similar injury.
He came on as a substitute just before the hour at the DW Stadium, scored with a superb long-range strike after 72 minutes and then hobbled off to obvious frustration nine minutes from time.
When asked about the player's disappointment, Mancini said: "It is normal.
"He played against Chelsea and played very well. He came back after injury, now he played 20 minutes and had a hamstring (injury).
"We are disappointed because James was in good form in this moment."
Mancini, speaking at a press conference to preview Everton's visit to the Etihad Stadium, was also asked about the anticipated loss of Yaya and Kolo Toure to the African Nations Cup in the new year.
The absence of midfield linchpin Yaya Toure during the 2012 tournament coincided with a frustrating spell for City during their title-winning campaign.
Mancini would clearly be happy for the Toures, and fringe player Abdul Razak, not to link up with Ivory Coast for the month-long competition but is not sure if opting out is realistic.
He said: "If we lost Yaya and Kolo and maybe Abdul, who also has not played a lot of games here but maybe in January could be important if we have two or three players injured and we don't have other players - I hope that maybe they don't go in this competition.
"We talk and we need to talk more with their manager but it is difficult."
City are undefeated in the Premier League and just a point behind leaders United, but their performances have not been as convincing as last season.
Their Champions League campaign has also been another disappointment, with City failing to progress from the group stage for a second successive year.
Mancini joked that it may therefore be in City's interests for UEFA to expand the competition, as has been suggested.
He said: "Maybe with 64 (teams), we go on in the second stage!
"I say 'Thank you (Michel) Platini' - but I think he talks about three years' time."