Former American tennis player Andre Agassi didn't back down while describing how talented rising Nick Kyrgios is.
Kyrgios, 22, is widely seen as a player capable of landing Grand Slam titles and becoming world No. 1 in the future.
The Australian has captured three ATP titles and reached a career-high of No. 13 in the world.
Kyrgios has earned at least one win against the Big Four members Novak Djokovic, Rafa Nadal, and Roger Federer at the ATP level so far in his career.
He also defeated Scot Andy Murray at the Hopman Cup a year ago.
"I mean, obviously Nick Kyrgios, I’ve always mentioned him as one heck of a talent," former world No. 1 Agassi told the World Tennis Challenge.
Agassi, an eight-time Grand Slam champion, also had a high praise for Germany's Alexander Zverev.
Zverev, 20, has had a great season so far -- winning two Masters 1000 titles and reaching a current career-high of No. 3.
The world No. 3 is ready to make his debut appearance at the upcoming Nitto ATP Finals, 12-19 November.
Agassi certainly believes Kyrgios and Zverev are the ones to be closely followed.
"Sascha Zverev, I mean, he is a beauty to watch and he's only going to get better. He has a lot of tools, a lot of strengths, a lot of upside. There's a lot of ways to improve and I think it’s not really predicting anymore with the year he's had, but these are, I think, two guys that really set the stage for the standard of the next generation," Agassi added.