Sir Alex Ferguson has confirmed that Alan Smith suffered a broken leg and dislocated ankle in the defeat against Liverpool.
The combative Yorkshireman landed awkwardly after sliding to block a John Arne Riise shot late in Saturday's tie, and has subsequently gone to hospital.
"He's broken his leg and dislocated his ankle," said Sir Alex. "It's a bad one. He's gone to hospital. It looks very long term. It's one of the worst I've seen.