Aston Villa captain Stiliyan Petrov has been ruled out for at least two months, manager Gerard Houllier has confirmed.
The midfielder was hurt in the first half of Villa's 1-0 loss to Sunderland on Saturday, and may now need an operation on his knee injury.
"Unfortunately I think we have lost Stiliyan Petrov for maybe at least two months," Houllier said on the club's website.
"We will see if he needs an operation or not - we will know that by the middle of the week.
"It is a shame because he was getting up to a good level. It was a very unfortunate accident."