Aston Villa manager Gerard Houllier has revealed skipper Stiliyan Petrov could be out of action for at least two to three weeks with a knee injury.
The Bulgaria international suffered the setback during the first half of Saturday's 1-0 defeat by Sunderland at the Stadium of Light.
Midfielder Petrov, who was replaced by Steve Sidwell after 38 minutes, is to have a scan to determine the extent of the damage.
But, if Houllier's worst fears are realised, Petrov will definitely miss the midweek Carling Cup tie with Burnley and the derby clash with Birmingham at Villa Park next Sunday.
Houllier said: "He will have a scan. I think it could be a lateral ligament injury which may mean two or three weeks (out of action) if it is a grade one injury.
"If it's a grade two or three, maybe it could be longer."