United's players travelled to Los Angeles on Sunday with David De Gea, Sergio Romero and Joel Pereira all part of the squad.
The Red Devils kick off their tour against LA Galaxy next week before matches against Real Salt Lake and Manchester City - and Mourinho has revealed all three stoppers will feature, reports the Manchester Evening News.
"The first match [against LA Galaxy], Romero does not play," Mourinho told MUTV during an impromptu chat. "We play David for 45 and the kid for 45.
"In the second match [versus Real Salt Lake], David does not play. We play the kid for 45 and Romero for 45. The third match against Man City, we don't play Joel. We will play David for 45 and Romero for 45."