Kylian Mbappe can be a star of world football for the next 15 years, according to Belgium midfielder Kevin De Bruyne.
France and Mbappe meet De Bruyne and his international colleagues in Tuesday's World Cup semi-final in St Petersburg.
The teenage forward sprung to prominence 18 months ago after breaking into Monaco's first team.
Manchester City favourite De Bruyne conceded he knew little about the youngster before he scored in both legs of a remarkable Champions League last-16 tie against his club that finished 6-6 on aggregate, with the Ligue 1 side prevailing on away goals.
"He's become a star in France," the 27-year-old told a news conference when discussing Mbappe, who moved to Paris Saint-Germain last August in a loan move since made permanent.
"When I was playing against Monaco he had only played about 10 matches. He hadn't played a lot of football, to tell the truth.
"At that time I didn't know him but now he's been playing for a year and a half. He plays for a great team. He's played a lot for France, he's played a lot of Champions League. He's a different player now."
Mbappe sat out training at Krestovsky Stadium on Monday but France boss Didier Deschamps said he expects his whole squad to be fit to face Belgium.
"He's a different player now," De Bruyne added. "He's a star for the next 15 years. He's had a fantastic year – he can even improve, if that's possible.
"He can be dangerous for us but we are going to try and stop him from playing."