Paul Scholes is set to be ruled out for United until into the New Year, reports the Manchester Evening News.
United will send the 32-year-old midfielder to a specialist after a scan last week proved inconclusive on the knee injury he sustained in training last Monday in Kiev before the Champions League match.
Sir Alex Ferguson reported that Scholes had felt a 'click' in his knee during the session in Dynamo's Olympic Stadium.
United couldn't fly their midfielder home early but after returning from the Ukraine in the early hours of Wednesday morning, he was sent for a scan.
Reds boss Fergie said the results didn't show clearly the problem but Scholes had a further appointment to try to ascertain the damage.
But there are serious fears that Scholes will be told he will be out for three months, leaving him looking at a return to fitness in February.