Manchester United defender Nemanja Vidic will undergo a scan after he was stretchered off with a knee injury during his side's 2-1 UEFA Champions League defeat at Basel on Wednesday.
The Serbian defender twisted his right knee in a challenge with Basel striker Marco Streller a minute before the break in Switzerland.
The 30-year-old appeared to be in quite some pain and had to be stretchered from the field, to be replaced by Jonny Evans.
With the Red Devils failing to qualify for the knockout stages for the first time in six years, Vidic's injury completed a miserable night for the Premier League champions.
United boss Sir Alex Ferguson revealed after the game that he fears Vidic has suffered medial ligament damage, which could sideline him for a significant amount of time.
The former Spartak Moscow man has already missed the opening two months of the campaign with a calf injury, but had looked back to his best in recent weeks alongside Rio Ferdinand.
The loss of the influential captain, who left the stadium on crutches, would represent a further blow to United's chances of closing the five-point gap between themselves and Manchester City at the top of the Premier League.