Manchester City playmaker David Silva is likely to miss the start of his side's Champions League campaign.
The Spaniard returned early from international duty this week for treatment on a thigh strain.
Manager Manuel Pellegrini has confirmed the 27-year-old will not feature in this weekend's Barclays Premier League game at Stoke and will probably not be available to face Viktoria Plzen in Europe on Tuesday.
That makes the derby against Manchester United at the Etihad Stadium on Sunday a possible return date.
Pellegrini, speaking at a press conference to preview the trip to Stoke, said: "We will see next week what happened with him. We hope he can be, not sure - we will try for the derby."
Captain Vincent Kompany, who has been sidelined since suffering a groin injury in the season-opening game, is nearing a return but he too will not play at Stoke.
Pellegrini said: "Kompany is okay but I think it is a big risk for him to play three matches in one week.
"He needs two or three more days to be 100 per cent."
Fellow defender Micah Richards is still out with a hamstring complaint and, in a further addition to the problems at the back, Pellegrini revealed left-back Gael Clichy also has a minor knock.
He said: "It is not very important, (but) he is missing this weekend."
City's start to the campaign has been plagued by defensive injuries with centre-back Matija Nastasic missing the first two games with a knee problem.
New signing Martin Demichelis has also been ruled out with a knee injury suffered in training. Pellegrini estimates he will be missing for six weeks.