LONDON (Reuters) -- Aston Villa captain Stilian Petrov will be out for at least two months after the midfielder injured his knee in Saturday's Premier League defeat at Sunderland.

"Unfortunately I think we have lost Stilian Petrov for maybe at least two months," Villa manager Gerard Houllier told the club's website (www.avfc.co.uk) on Monday.

"We will see if he needs an operation or not -- we will know that by the middle of the week."

The Bulgarian international picked up the injury in the first half of Saturday's 1-0 defeat, which left Villa in 10th place after nine matches.

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