Brazilian midfielder Fred is expected to be thrust into the starting XI, but Mourinho has said that the team "is not going to be very different" from the one that ended the 2017-18 season.
"It's not going to be very different. We basically have the same players," Mourinho told beIN Sports.
The players we have bought - one is a goalkeeper cover, one is a 19-year-old kid, so in fact we have one new player, which is Fred. So, of course, our team is not going to be very different."
United will open their 2018-19 Premier League campaign at home to Leicester City on August 10.