Romelu Lukaku could not turn down the chance to join Manchester United after hearing Jose Mourinho's plan to "rebuild the club,'' but cautioned that the Old Trafford club aren't getting a forward at the level of Bayern Munich's Robert Lewandowski or Real Madrid's Cristiano Ronaldo.

For much of the summer it had appeared that the 24-year-old was bound to leave Everton for Chelsea, only for United to swoop in.

Mourinho was in charge when Lukaku was given the green light to leave Stamford Bridge, but three years on he now sees the striker as a key piece of the puzzle at Old Trafford.

United forked out an initial £75 million for the Belgium international, whose mind was made up by his manager's plans rather than the persuasive powers of close friend Paul Pogba.

"We were just on holiday together,'' Lukaku said of the United and France midfielder, who he was away with in Los Angeles as the move was completed.

"At the end of the day I had to make my own choices.

"It was the conversation I had with the manager that really convinced me the most, the plans and how he wanted to rebuild the club and he wanted me to be part of it.

Romelu Lukaku has big boots to fill at Manchester United. AP Photo/David J. Phillip

"I am grateful for the chance.''

Lukaku has big boots to fill following the exit of injured top scorer Zlatan Ibrahimovic and the club's all-time leading marksman Wayne Rooney.

However, the 24-year-old's impressive ratio for Everton suggests he is ready to step up at Old Trafford -- and the striker is clearly raring to go.

"It feels great [to be a United player],'' Lukaku said in Washington. "It is something I always wanted.

"I always wanted to play for a club of this stature. Now I am here I want to take my chance and try to deliver as much as I could for the club.

"I don't want to talk about personal ambitions. I just want to work hard on a daily basis and win as many games as I can.''

Lukaku has certainly been made to work hard during United's tour of the United States, training with his new teammates for the first time within an hour of his move being made official.

Mourinho has praised the new boy at nearly every public appearance after a promising start, following up his first goal in a United shirt at Real Salt Lake with another in the 2-0 derby win against Manchester City.

"It has gone well for the team,'' Lukaku said of the build-up to the 2017-18 season. "Everybody is well prepared.

"We are working really hard and delighted to be here and we need to keep going.''

Lukaku highlighted that his goal was to join a winner, and feels has done that at Old Trafford.

"For me, it's all about winning,'' he added. "I want to win and now I'm at a club where winning is the most important thing.

"It's something inside of me, so I just want to win and I want to help my teammates deliver wins game in, game out.

Lukaku said, at 24, he has not yet reached his prime and is far from the likes of Lewandowski and Ronaldo. Getty

"It's always been like that. I've been a guy who is working to be a pro since I was 11 years old, so I just have a goal to win as many trophies as I can.

"At the end of the day, to play for a club like Manchester United is something that I've always wanted. It's an opportunity I have now and I want to grab this opportunity.''

Lukaku's goal against City was a goal any of Europe's elite would have been proud of, but Lukaku knows he is a way off being considered in the same bracket as the likes of Lewandowksi or Ronaldo.

"Yeah, of course [I want to reach that level] but winning trophies at the end of the day [is key],'' Lukaku said. "At the end of the day you want to win trophies.

"I'm a goalscorer, I've always scored goals throughout my career. Also in Europe, when I played in the Europa League, my record is really good.

"Now I think the Champions League is the next stage where I have to prove myself and the club wants to do well in it as well.''

Asked if he was at the level of Lewandowski and Ronaldo right now, he quickly replied: "No, no, no -- I'm far from that level.

"But it's the level I want to aim for. But it's all about the team. I want the team to win trophies and I'll do everything that I can in my powers to make sure the team wins.

"Keep improving -- there is always room for improvement. I just want to become the best player that I can be.

"I will never say it's good enough. I will always say that I can improve.

"I'm 24 years of age. I can't say I'm the complete package. I can't say I'm in my prime.

"There is a lot of work to be done and I'm delighted that there is still work to be done. That means I can become even better than I am now.''

Lukaku may not yet be at his peak, but Mourinho has been pleased by what he has seen, praising the new boy at nearly every public appearance.

The United boss speaks about Lukaku with similar excitement to how he once did about Didier Drogba - a player Lukaku idolised and worked with at Chelsea.

"Not really, I'm different,'' Lukaku said when comparisons to the job Drogba did for Mourinho were brought up.

"Drogba is more of a hold-up player, a target-man. I prefer to have ball to feet and run in behind.

"It's something we're totally different at. We might have physical similarities but I think we're totally different players.

"And I'm Romelu Lukaku -- at the end of the day I want to create my own history. I'm at Manchester United, he was at Chelsea.''