Lukaku was bought from Everton to replace Zlatan Ibrahimovic, who was released by United after suffering a serious cruciate ligament knee injury last season.
But Mourinho believes Lukaku and England striker Rashford can play effectively alongside each other, rather than the former leading the line alone, and plans to try them out together on the remainder of the tour.
Rashford scored twice in his 45-minute outing, while Lukaku’s United debut was less memorable, the striker missing a sitter minutes after coming on.
“Today Marcus was in a different team than Lukaku,” said Mourinho. “We’ll also try them both in the same team, which I think can also work.
“Lukaku is more of a target man with his back to opponents. He’s a point of attack to everyone, he’s really fast and a good thing for me today was that he’s a team player. He wasn’t worried about himself, he was worried about the improvement of the team.”
Newly-appointed United skipper Michael Carrick echoed Mourinho in suggesting Lukaku and Rashford could form a strike partnership, the like of which has not been seen at Old Trafford since Dwight Yorke and Andy Cole.
“Maybe,” said Carrick. “He [Mourinho] changed it tonight and I’m sure we’ll change it again in the weeks coming up. We’ve got games coming thick and fast and this is the time you want to try things. Two up front worked well in both halves.”
Rashford, who scored eight goals in 18 appearances in his first season and 11 in 53 games last term, has hit the ground running in pre-season and looks determined to prove a point to Mourinho ahead of the new campaign.
The 19-year-old has bulked up over the summer and made himself more physically imposing to opponents, although not, Mourinho claimed, at the expense of his most formidable asset – his pace.
“It’s just a natural evolution of a kid and an accumulation of minutes on a pitch,” said Mourinho. “Your body changes when you’re a young kid. He’s already taller than when I arrived 13 months ago – he’s three centimetres taller.
“He’s put some muscle, but without any kind of specific work, because his speed is his most important quality.
“Last season in this period, everyone was saying it would be difficult for me to play him. But he was one of the players with the most appearances last season.
“He played the important matches in the Europa League, which is like a pre-Champions League, and he’s learning a lot.
“He’s a great pro, he has great attitude.
“Last season he wasn’t scoring goals and was missing a lot of chances, which was not a drama because that’s part of the evolution. We know he’s going to score more goals than last season.”