The clubs last met in the FA Cup in a stormy affair two years ago, when Fulham finished with nine men as United came from behind to win 3-1, thanks to two goals from Bruno Fernandes and a cheeky backheel by Marcel Sabitzer.
Ruben's side won the most recent clash, in the league, with a 1-0 triumph at Craven Cottage last month, as Lisandro Martinez scored the winner.
Ticket are still available for the visit of Marco Silva's west Londoners and you can purchase by clicking here.
This will be the first-ever United game to feature semi-automated offside technology, following Thursday's FA statement on the subject.
The eight fifth-round ties are split across four days, starting with Aston Villa's match with Cardiff City on the final day of February, and finishing on the Monday (3 March), when Nottingham Forest take on Ipswich Town.