Romelu Lukaku has revealed he chose to sign for Manchester United this summer because he believes Jose Mourinho will "push him" to become a better player.
Lukaku scored his first goal following his £75 million move from Everton in a 2-1 win over Real Salt Lake on Monday.
The 24-year-old has worked with Mourinho before during a brief spell together at Chelsea at the start of the 2013-14 season and says he is already feeling the benefit of being reunited after just a week of training in the United States.
He said: "He knows what I can bring to the team and he's someone who is pushing me. I push myself too, but he makes me a better player.
"I think I learned a lot from him in the last week and I'm glad I can work with him. "
Lukaku didn't manage to open his account on his United debut in the 5-2 win over LA Galaxy in California on Saturday but said he was "happy" to get the first one out of the way in Utah.
He added: "I'm happy for my goal. There is still a lot of work to do, as a team we know we need to be much better.
"But I'm glad I'm here because you really see it's a big club and that was the challenge I wanted."
Before signing at Old Trafford, Lukaku was heavily linked with a return to Chelsea, especially after manager Antonio Conte made clear his plan to ditch Diego Costa.
United's swift move caused some surprise, coming in the middle of drawn-out negotiations with Real Madrid for Alvaro Morata.
Lukaku, however, insists United was always his first choice.
He said: "I am very happy now. This is the job I wanted. I have to make sure that I stay focused and have the same ambition I've always had. And just work hard, that's the key to success."