Manchester United have confirmed captain Nemanja Vidic has been ruled out for the season as a result of his knee injury and he is set to undergo surgery.
The defender was stretchered from the field on a miserable night for United on Wednesday, as they were eliminated from the UEFA Champions League after defeat to Basel.
Manager Sir Alex Ferguson feared Vidic had suffered a serious injury and it has now been announced the Serbia international has sustained a ruptured cruciate ligament after clashing with Marco Streller.
"We thought it was a bad one," said Ferguson. "He's out for the season. It's not unexpected, but it's still bad news.
"He'll see a specialist on Monday to work out the progress of when he has the operation. It won't be immediate as we have to let the swelling come down."
Losing Vidic, who is widely considered to be United's best defender, is a huge setback for the club at a time when they are being badly hit by injuries.
Michael Owen, Anderson and Tom Cleverley are among those already rehabilitating and the latest problem could force Ferguson to act in the January transfer window.
Although Phil Jones, Jonny Evans or Chris Smalling are all capable of acting as Vidic's replacement, United may want to bring in an experienced alternative.
After the Champions League shock, Ferguson's main focus will now be upon chasing Manchester City in Premier League.
And on Saturday, United could move to within two points of their rivals with a win over Wolves, while City visit Chelsea on Monday.