MELBOURNE, Australia -- - This is one quarterfinal nobody saw coming at the Australian Open.
With a straight-sets win Sunday over third-seeded Dominic Thiem, the U.S. Open champion and Australian Open runner-up in 2020, Grigor Dimitrov advanced to a showdown with Aslan Karatsev.
Yes, that Karatsev - the Russian ranked No. 114 who is playing in his first Grand Slam tournament. Dimitrov making a fourth quarterfinal at Melbourne Park isn't entirely an upset.
The 29-year-old Bulgarian has been ranked as high as No. 3, won the ATP Finals, and already led his friend, Thiem, 3-2 in career head-to-heads, although this was their first at a major.
Despite his lengthy tennis pedigree, Dimitrov has never been past the semifinals of a major. So he's wary of somebody like Karatsev.
"If you're here, it's for a reason -- there's no doubt about it," Dimitrov said after his 6-4, 6-4, 6-0 win. "Whether it's a fairytale or not, it's a match - you've got to be ready."
Karatsev earlier added a win over No. 20 Felix Auger-Aliassime, coming back for a 3-6, 1-6, 6-3, 6-3, 6-4 victory, to an earlier one over No. 8 Diego Schwartzman.
He'd failed in nine previous bids to qualify for a Grand Slam tournament, but finally succeeded in Doha last month, when qualifying for the Australian Open was held off shore for the first time because of restrictions in place for the COVID-19 pandemic.
He's now just the third qualifier to get this far in Australia in the professional era, the first since Goran Ivanisevic in 1989. The last man to get to the round of eight in his first Grand Slam appearance was Alex Radulescu at Wimbledon in 1996.
And not since Patrick McEnroe -- John's brother -- in 1991 has a man ranked as low as 114th made it to the Australian Open quarterfinals.
"I was working a lot, and it just happened right now," the 27-year-old Karatsev said of his recent streak.
"It's like you never know when it happens. It just happened here."
Thiem said he had a few issues on Sunday, but didn't want to elaborate or use them as excuses.
It was clear, though, that he was still fatigued after having to come from two sets down to beat Australia's Nick Kyrgios in five sets on Friday night.
"Some little physical issues, plus a real bad day, plus the fact that, well, he's a great player," Thiem said. "So a combination of those three things, and a result like that can happen."
"The thing also is that I'm also not a machine," he added. "I mean, sometimes I would like to be, but there are really, really bad days.
"As soon as you're not 100% there on the court on this level, then results like this come up, and that's exactly what happened today."
In other fourth-round matches, U.S. Open finalist Alexander Zverev beat No. 23-seeded Dusan Lajovic 6-4, 7-6 (5), 6-3 to move into the quarterfinals.
The sixth-seeded Zverev, a semifinalist in Australia last year, will next play top-ranked Novak Djokovic.