Belgium boss and former Everton manager Roberto Martinez heaped praise on Romelu Lukaku by claiming he can become the best striker in the world.
Lukaku has flourished since he was lured to Everton by then-manager Martinez in a club-record deal in 2014, and tops the Premier League's goalscoring charts with 21 this season.
The 23-year-old Belgium international has refused to sign a new deal at Goodison Park amid interest from some of Europe's biggest clubs.
Martinez - who is back working with Lukaku in the national team - believes the sky is the limit for the ex-Chelsea striker.
"When you work with Rom, you understand he lives for the games. It's all about football in his life. He always wants to do more in training," Martinez told BBC's Football Focus.
"From a very young age, he had an incredible goalscoring threat. Any footballer that is special at the highest level, has to be outstanding at something.
"Rom is the goalscoring threat. From the age of 21 to 23, he has changed a lot. He wants to improve, he works on hold-up play and using his body. He has been working on his movement in the box.
"He's never lost the outstanding quality of scoring goals.
"At the age of 23, I always believed he had the possibility of becoming the best number nine in world football because he has absolutely everything."
Lukaku will take to the field on Saturday when Group H leaders Belgium host second-placed Greece in Brussels.