After a disappointing two seasons at United, Lukaku has established himself as top striker with Inter Milan after netting 34 goals in his debut season with the club.
The Belgian carried that form into the current season as he has netted 15 goals in 18 matches across all competitions, which he feels puts among the best in the world.
"Now? In the past five months, yes," the Belgian told Voetbalmagazine. "I don't want to rank that group from one to five, but I'm part of it right now."
Lukaku also credited Jose Mourinho and Roberto Martinez for his development during his spells with Everton and United.
"Mourinho taught me to work better with the team, both in terms of pressing and to position me better on the field. Just look at what he's doing with Harry Kane now.
"I used to love vertical football. I found myself to be most dangerous when I was facing the goal. I am fast, I can eliminate my direct opponent with a dribble, or swerve to the left or the right.
"That was my game in the past, also because I was often in teams that played on the counter. But the national team has obliged me to adjust my playing style.
"With Belgium, we quickly became a team that had the most possession and got the least space [to play in]. Roberto Martinez did everything he could to make me feel more comfortable with my back to goal, both with the national team and back at Everton.
"At the age of 20, I still had a lot to learn. But I soon realised that if I could train that aspect of my play, I could do what I wanted in a match."
