Lukaku made his United debut as a second-half substitute as Jose Mourinho’s men cruised to a comfortable 5-2 win against LA Galaxy.

The Belgium ace looked eager to please and snatched at a couple of chances to open his account.

But Carrick is convinced the £75m man will come good - provided he doesn’t change and keeps doing what has got him to Old Trafford in the first place.

Carrick wants Lukaku to be his own man and not try to emulate other strikers that have gone before him.

He said: “It’s early days. He’s had one week’s training and 45 minutes, so you can’t come to any conclusions.

“But we know what he’s all about, there’s no surprises. We all know exactly what he brings and that’s why he’s here.

“He’s not going to change his game because he’s come here. He does what he does best and obviously he’s been brought here to score goals. I’m pretty certain he will do that this season.

“(Zlatan) Ibrahimovic was terrific for us, but Rom is his own man. When I came it was Roy Keane who came up in terms of comparisons, but I’m my own man.

“Whoever comes in, you’re always your own man. He’ll be judged like anyone else on what he does through the season - and I’m sure he’s ready for that.

“The scrutiny and everything will go up a level from what he’s used to. But I’m sure he’s prepared for that and I’m sure he will do well.”

Lukaku had to sit and watch Marcus Rashford steal his thunder, with the England star opening the scoring inside two minutes then grabbing a second before half-time.

And Mourinho’s delight at Rashford's rapid rate of development was certainly in evidence as the Manchester United boss discussed his options in attack.

“It’s just the natural evolution of a kid,” said Mourinho. “You change your body when you’re a young kid.

“He’s already taller than when I arrived 13 months ago - he’s three centimetres taller - and he put on some muscle, but without any kind of specific work because his speed is his most important quality.

“He was in a different team than Lukaku [against the Galaxy] but we will also try both in the same team, which I think can also work.

“Last season everyone was saying it would be difficult for me to play Marcus - but he was one of the top in appearances for the team. He’s learning a lot, a great professional, great attitude.

“Last season he was not scoring goals and missing a lot of chances, which was not a drama, because that’s part of the evolution. We know he is going to score more goals than last season.”

Mourinho took the chance to experiment with a back-three, but his MLS opponents were so poor that the result was never in doubt.

Marouane Fellaini joined in the fun to make it 3-0 before half-time and goals after the break from Henrikh Mkhitaryan and Anthony Martial completed the rout.

Late strikes from Galaxy duo Giovani dos Santos and Dave Romney offered little consolation to the hosts in a game which United dominated from start to finish.

Carrick admits the Red Devils have to challenge for the league title this season and he added: “We’ve got to feel that. It’s up to the manager whether more players come in or whether they don’t.

“That’s not for us to worry about. But the title has got to be aim. We have to challenge the best and be the best. It has to be that philosophy at this club no matter what happens and this season is no different.

“We finished last season with a trophy and we’ve got a good feeling going into this one.

“We’ve got the Super Cup against Real Madrid coming up pretty quick, so we’ve got to be focused on that really and then the season ahead.”