Like United and West Ham, Fulham and Blackpool also face a replay at Bloomfield Road after their first game ended in a 1-1 draw at Craven Cottage.
The draw throws up the potential for a return to Old Trafford for Dimitar Berbatov as the striker was still a United player when the two sides faced earlier this season.
The ties are scheduled to take place on January 26th/27th.