Manchester United striker Romelu Lukaku believes manager Jose Mourinho has already made him a better player.
Lukaku, 24, only completed his move to United from Everton for a reported £75million on July 10.
The Belgium international scored his first goal for the club on Monday, netting in a 2-1 friendly win over Real Salt Lake.
Lukaku - who scored 25 Premier League goals last season - said Mourinho, his former boss at Chelsea, had already helped him improve.
"He knows what I can bring to the team and he's someone who is pushing me," he told UK newspapers.
"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.
"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."
Lukaku enjoyed a fine stay at Everton, scoring at least 10 league goals in each of his four seasons at Goodison Park.
But he is ready to fire for United, saying: "I'm very happy now.
"I have to make sure I stay focused and have the same ambition I've always had and work hard - that's the key to success."
United are next in action with a derby clash against Manchester City at the International Champions Cup on Thursday.