United ended yesterday's 4-0 Premier League win over West Ham with Michael Carrick and Patrice Evra at centre-back and Ryan Giggs at full-back after Gary Neville and Wes Brown added to an already-lengthy injury list.

Ferguson is now hoping Nemanja Vidic will recover from flu in time to partner Carrick, while Darren Fletcher is expected to continue at right-back.

"Evra must be the smallest centre half in the world," said the United boss. "But he's a good reader of the game. He's quick and determined.

"I don't know where I'm going to get a back four for Tuesday. Probably Nemanja Vidic will be back from flu and I'll probably play Carrick alongside him."

United's injury list:

Gary Neville - groin

Nemanja Vidic - flu

Rio Ferdinand - calf

Jonny Evans - calf

John O'Shea - thigh

Rafael - injury

Fabio - groin

Edwin van der Sar - knee

Wes Brown - limped off

Owen Hargreaves - knees