Romelu Lukaku will come under the microscope at Manchester United, warns captain Michael Carrick

The £75m frontman was unable to get on the scoresheet in Saturday's 5-2 win over LA Galaxy

Romelu Lukaku made his first Manchester United appearance on Saturday (Getty)

The Old Trafford microscope will be unlike anything Romelu Lukaku has previously experienced, Manchester United captain Michael Carrick has warned.

Lukaku made his United debut as a half-time substitute in a 5-2 stroll over LA Galaxy, as Jose Mourinho’s men enjoyed a winning start in the first of five Stateside friendlies in the space of 12 days.

The £75m frontman was unable to get on the scoresheet after spurning a presentable one-on-one. Instead, it was Marcus Rashford who demonstrated his predatory instincts with a first half brace.

But while Lukaku produced some promising hold-up play, new United skipper Carrick knows that the Belgian will inevitably be judged on his goal return for Jose Mourinho’s men, particularly given his price tag.

“The scrutiny will go up a level from what he’s used to,” said Carrick. “It’s a massive jump. I even found that coming from Tottenham. You can’t really explain to people unless you go through it.

“He’ll find the same as time goes on. But having Premier League experience is a massive bonus. He’ll know what to expect and how things work from week-to-week.”

Lukaku spent a full week training with United in Los Angeles, with Mourinho’s men now in the 4,000ft altitude of Utah preparing to face another MLS side, Real Salt Lake, in the early hours of Tuesday morning.

The former Everton man has offered few shocks on the training field so far after United were well aware what they were recruiting as a replacement for the out-of-contract and injured Zlatan Ibrahimovic.

Carrick said: “I think we all know what he’s all about. There’s no surprises there. We all know exactly what he brings, that’s why he’s here. He’s not going to change his game. Let’s hope he brings us what he does best.

“Obviously, he was signed to score goals and I’m pretty sure that’s what he’s going to do for us.”

Fellow summer signing Victor Lindelof also made his United debut against Galaxy, with Mourinho still on the look-out for a further two recruits.

Nemanja Matic, Eric Dier and Ivan Perisic are all on United’s wish-list, yet even if the club’s recruitment drive has reached a conclusion, Carrick believes a title challenge is an inevitable objective.

“The aim has to be challenge with the best and to be the best, no matter what happens [in the transfer market],” said the 35-year-old.

“That’s always the case at this club and this season is no different.

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

Marouane Fellaini, Henrikh Mkhitaryan and Anthony Martial all found the net in addition to Rashford, in what was a particularly comfortable win against a pretty feeble Galaxy outfit.

Carrick added: “It’s always nice to win, 45 minutes for everyone and they all came through it.

“We scored some goals and got a feel of it again. That first match is always one to get out the way. All round, it was pretty positive really.”