FC Basel's (FCB) Marco Streller (L) fights for the ball with Nemanja Vidic of Manchester United during their Champions League Group C soccer match in Basel Dec 7, 2011. [Photo/Agencies]

Sir Alex Ferguson's disappointment was compounded by a knee injury sustained by captain Nemanja Vidic that saw him stretchered off shortly before halftime.

"We don't know at this moment in time," said Ferguson when asked about the severity of the injury. "We think it's the medial ligament. Hopefully that's the worst of it."

Nemanja Vidic of Manchester United is carried off the pitch after fighting for the ball with FC Basel's Marco Streller during their Champions League Group C soccer match in Basel Dec 7, 2011. [Photo/Agencies]

As last season's beaten finalists wallowed in the misery of one of their most damaging defeats in recent memory, Basel were left to reflect on a win that opened up the door to the last 16 for the first time since 2002-03.

"What can I say? I'm very proud," said Heiko Vogel, who was appointed Basel coach in October after Thorsten Fink left for Hamburg.

"Tactically, mentally, physically - everything worked right. I'll leave the superlatives to you (the media). I think we deserved the victory. I'm beaming with pride."

The Swiss champions now face the prospect of a last-16 tie against one of the tournament's heavyweights, with holders Barcelona, Real Madrid, Bayern Munich, Inter Milan, Arsenal and Chelsea all potential opponents.

Agence France-Presse