Manchester United are waiting for defender Nemanja Vidic to undergo a scan that will determine the extent of the knee injury he sustained in the Champions League victory over Roma.

The imposing Serbian centre-half landed awkwardly after contesting a high ball during the first half, and was forced to limp off with just 30 minutes played.

"I pray it's not serious, because he is such an integral part of our team," said United manager Sir Alex Ferguson.

"It might just be a nerve injury but we can't be sure at this moment."

Vidic's central defensive partnership with Rio Ferdinand has been the bedrock of United's success this season, with just 15 goals conceded in 32 league games.

Utility man John O'Shea came on for Vidic at the Stadio Olimpico, while left-sided defender Mikael Silvestre was named in the squad after an absence of over six months with a knee ligament injury.

Club captain Gary Neville is also thought to be nearing a return to first-team action.

The England right-back has not started a game for his club since March last year, when he sustained an ankle injury in a home game against Bolton.

Subsequent comeback attempts have been thwarted by a succession of injuries, but he has come through recent reserves games unscathed.

Tom Williams / Eurosport