Marcus Rashford had to be taken off midway through the second-half with what Mourinho thought was cramp but the 19-year-old indicated he felt a problem with his knee.
Eric Bailly returned from international duty with the Ivory Coast injured. Phil Jones was also nursing an injury after starting in the weekend draw with Liverpool and remained on the sidelines.
Michael Carrick, Marouane Fellaini, Paul Pogba and Zlatan Ibrahimovic are Mourinho’s injured big four.
United face Huddersfield where Marcus Rashford and Eric Bailly are injury doubts for Manchester United's Premier League trip to Kirkless Stadium on Saturday.