The striker limped off towards the end of United's 3-0 victory overBurnley yesterday, having scored United's first goal and set up thesecond for Wayne Rooney.
Facing an op: Dimitar Berbatov could be out for three months
MANCHESTER UNITED FC: All the latest news from across the webOwen Coyle is as good as Sir Alex Ferguson, claims Andy ColeSir Alex Ferguson insists City can afford to buy anyone. even Lionel MessiBut his joy was curtailed when a long-standing knee injury flared up again despite United's warm-weather training in Qatar last week.
Berbatov often seemed in discomfort during the game, particularly after a knock to his left knee, and United may decide to send him for surgery to cure the ligament problem.
Any long-term absence for the Bulgarian might force manager Sir Alex Ferguson into the market during the current transfer window.