Jose Mourinho, according to Roma striker Tammy Abraham, has turned him into a "monster" and a more aggressive player.
Abraham moved to the Italian capital from Chelsea in the summer and has scored five goals so far this season.
A slump in Roma's form has coincided with a goalless streak for Abraham, who has scored just once in his last eight appearances.
However, Abraham's choice to leave the Premier League has been validated at the international level, with the 24-year-old featuring in England's win over Albania on Friday.
Asked what Mourinho had taught him at the Stadio Olimpico so far, Abraham replied: "Just be a monster really!
"I think one of the things he said was I was too much of a nice player and that you have to show that aggressiveness as you're getting older as a striker.
"It's not always about being nice on the pitch. You need that character, you need that presence to frighten defenders and I think that's something I'm learning and getting better at.
"I felt the sooner I settled in the better, and started learning different types of football and different styles. I've gone to spread my wings and hopefully, I can keep up the level of performances I need to stay in the team.
"Of course (the World Cup) was in the back of my mind but really I just wanted to play football. For me, it's still a young career and I just felt I needed to go out and play some games to improve and hit the highest levels, and hopefully, I can keep striving on."