Manchester United fear Nemanja Vidic could be out for the season after suffering a knee injury in their 2-0 win at Roma.

The Daily Mail says Vidic had tests on his injured knee at a Manchester hospital yesterday but it is understood that the Serbian's leg was so badly swollen it was difficult to assess the extent of the damage caused when he fell awkwardly during United's 2-0 win at the Olympic Stadium.

Vidic, 26, needs a more detailed examination this morning with United's medical staff resigned to the fact that he has suffered ligament damage.

The centre half looks to be out for a couple of weeks at least and perhaps will not play again this term.

It would be a big blow to United's chances of winning the Barclays Premier League and the Champions League and would bring back painful memories of last season when a sudden rush of injuries left Ferguson's side unable to get past the last four in Europe.

A United source said last night: "Nemanja came in this morning but could hardly walk. His knee is swollen and he did not look very happy after his first scan."