Dominic Thiem suffered a gut-wrenching US Open loss tonight, but earned lofty praise from Roger Federer in the aftermath.

Thiem built a two-set lead only to see 2009 US Open champion Juan Martin del Potro fend off match points and rally past the sixth-seeded Austrian in five gripping sets.

Asked to assess the Roland Garros semifinalist's future, Federer said Thiem will enjoy a 10-year run in the ATP Top 10.

"Sweet guy," Federer said of Thiem. "Really honest. Lovely to be around with. Hard working. Super hard working. He goes into the Rafa demographic where between matches, they just go really hard. I'm not like that, so I admire those guys that put their head down and work this hard."

Federer believes Thiem's time to win Grand Slam titles will come.

"Yeah, I love his backhand," Federer said of Thiem's one-hander. "Played him a few times. Got great power both wings. He's a power player that we have in the game. Yeah, he's going to be around for a long time.

"He's going to install himself in the top 10 easily, in my opinion, for the next 10 years. I'm sure he's going to create a lot of chances to win the biggest tournaments in the game."

Photo credit: Paul Zimmer/Mercedes Cup