Stefanos Tsitsipas and Nick Kyrgios hailed Denmark's Holger Rune as a potential multiple Grand Slam winner on Saturday -- but also have fears about the "tennis-obsessed" teen burning out.
The 19-year-old Rune shocked Novak Djokovic to clinch his first Masters title in Paris in November, cementing his status as one of the most promising young players on tour.
In doing so he became the youngest winner of the Paris tournament since an 18-year-old Boris Becker in 1986.
He is the first Danish man to break into the top 10.
Speaking ahead of next week's Australian Open, home hope Kyrgios called Rune "one of the best talents that we have in the sport".
"He's got the ability to win multiple Grand Slams. If I was Denmark, anyone who had Holger Rune, I would just make sure they support him, give him all the support," said the Australian.
"He's a young guy, he's super-young. He's doing everyone proud around him. He's going to deal with a lot of pressure and expectations."
Greek world number three Tsitsipas said Rune had "matured pretty fast", but expressed concern that he was so focused on tennis.
"I've seen him at the academy working hours and hours. He's obsessed with tennis. You can see how obsessed he is with the sport," he said.
"He lives, breathes and just I think thinks tennis all the time, which it's both good, but it might also have some downsides because you know you have to have other things in your life that excite you and brings joy.
"Tennis is an important part of your life. But I'm just worried about him burning out."
Despite his concern Tsitsipas, who like Kyrgios dealt with heavy pressure as a young emerging player, anticipates big things from the Dane, who made the French Open quarter-finals last year.
"He's a great athlete. He is able to beat anyone. He's a very disciplined guy when he plays matches," he said.
"I think this year could be his year, a year where he does much better than the year before."