Rooney sustained the niggle during training on Christmas Day, and was initially expected to be sidelined for a fortnight.

However, the Manchester United manager has revealed that the 27-year-old is expected to be out for a further two weeks, missing the highly anticipated tie with Liverpool on January 13, and also their FA Cup third-round clash with West Ham in the meantime.

"Wayne is still injured," Ferguson told reporters.

"It is not serious but it is going to take longer than we thought, probably another two weeks. He won't be fit for Liverpool."

However, there was some positive news for the Red Devils with defender Phil Jones and winger Nani both back in training this week after recovering from injury.