United secured Fred's signature earlier this summer, with the Brazilian joining the Red Devils from Shakhtar Donetsk.
The 25-year-old is expected to make his debut for the 20-time English champions in their pre-season friendly against bitter rivals Liverpool on Saturday night.
Mourinho has branded Fred "a technical player", and backed the Brazil international to be a link between the midfield and attack.
"Fred is a technical player. Having people in the squad like [Nemanja] Matic, [Marouane] Fellaini, [Paul] Pogba, even Ander [Herrera] - physical people, strong - we think a player like Fred, Andreas Pereira - more technical, more quality of passing, playing in short spaces - will maybe connect with the attacking players," Mourinho told reporters.
United have drawn with Club America and San Jose Earthquakes in their two pre-season matches thus far.