Manchester City hope James Milner will make a rapid recovery from his hamstring injury to play in next Sunday's derby against Manchester United.
But manager Roberto Mancini ruled the England international out of Saturday's Premier League game with Everton and Tuesday's Champions League match versus Borussia Dortmund.
Milner was hurt in Wednesday's 2-0 win over Wigan when he came off the bench, scored City's second goal and limped off.
"James is out for Everton," said Mancini. "We try to recover him for next Sunday but we don't know.
"He came back after injury, now he played 20 minutes and [injured] a hamstring. We are disappointed because James was in good form. He played very well against Chelsea."
Mancini also confirmed that Gael Clichy, who has an ankle problem, and Jack Rodwell, who has been sidelined since October with a hamstring injury, will miss the visit of Everton.
And the Italian is hoping his squad will not be further depleted in January by the African Cup of Nations.
City could lose Kolo and Yaya Toure plus Abdul Razak, who could all feature for Ivory Coast in South Africa.
"I hope that they don't go to this competition," Mancini said.
Mancini has held discussions with the trio and the Ivory Coast manager, Sabri Lamouchi, who played for him at Inter and added: "We talk and we need to talk more with their manager but it is difficult."
Yaya Toure is the only regular of the trio but the City manager believes his squad players could still have a part to play in the crowded winter fixture list.
"Abdul has not played a lot of games here but maybe in January he could be important if we have two or three players injured and we don't have other players," he added.