After sustaining a minor knee injury during Christmas day training, the England international is now due to be out for longer than the two weeks which were initially expected
Rooney sustained a minor knee injury 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 the Reds on January 13.
"Wayne is still injured," Sir Alex 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.