NEW YORK, NY, USA -- No.18 seed Ashleigh Barty of Australia finds herself in the fourth round of a Grand Slam event for the first time in her career following a 6-3, 6-4 victory over qualifier Karolina Muchova of the Czech Republic in the third round of the US Open on Friday night.

"It’s really cool," Barty told the press, regarding her first Grand Slam fourth-round showing. "I felt like we haven’t been far off a few times now, but to finally get this, it’s pretty cool."

In the first meeting between two all-court players who routinely rushed the net and sent up crafty lobs, it was Barty who withstood a fierce second-set comeback from the last remaining qualifier in the field to move into her first major fourth round appearance after one hour and 25 minutes of play.

The Australian used her first serve as the key to victory, winning nearly 80 percent of points when she got it into play.

"The whole summer, I felt like I’ve served pretty well," said Barty. "So when I can hit my spots on serve and try and dominate the court with my forehand as best I can, I feel like I can control most of my service games."

22-year-old Muchova, ranked World No.202, nearly equaled Barty in winners but had ten more unforced errors. The Czech, however, must be proud of making the third round in her first-ever Grand Slam main draw, which included a win over former World No.1 Garbiñe Muguruza.

"I actually felt like it was really high-quality tennis," said Barty. "To be honest, I have no idea how [Muchova's] ranked 200 in the world, she’s so much better than that, she really is. I know that this is probably one of the best weeks she’s ever had, riding that confidence, but regardless of that, she’s definitely better than 200 in the world."

In her maiden Grand Slam round of 16, Barty will meet the winner of the late-night match between No.8 seed Karolina Pliskova of the Czech Republic and Sofia Kenin of the United States.

Barty got off to a flying start, reaching double break point on Muchova’s first service game with a forehand past the net-charging Czech, and converting the first break point for a 2-0 lead after Muchova sent a backhand long.

The Australian No.1 seemed unstoppable as the set wore on, using her own forward momentum to put away a backhand volley and hold for 4-1. But Muchova started to crack bigger returns and groundstrokes, and finally found her chance to break midway through the set, blasting a forehand service return down the line for a clean winner to get back on serve at 4-3.

However, Barty, with tons of big-stage experience while still only 22 years old, immediately turned the set back in her favor, holding steady and forcing Muchova into errors, and broke right back to serve for the set at 5-3. In the next game, Muchova sent a backhand return long on Barty’s first set point, and the opening frame went to the seeded player.

Barty cracked open a huge lead in the second set, moving to a 3-0, double-break advantage; she took the third game of the set by winning an all-court rally on break point with a wily dropshot winner. But Muchova proved herself by holding her serve at 4-0, emerging victorious in a 26-point game which required her to save four break points.

Still, Barty was able to use her superb serve and court sense to move to 5-2, and serve for the match. The Australian blasted big forehands during the game to garner two match points, but huge, risky service returns by Muchova kept her in the game, and the Czech eventually claimed one break back to move to 5-3.

Muchova held with ease for 5-4, putting the pressure right back on Barty. Barty quickly raced to triple match point, but again blinked, squandering the first two chances with backhands gone awry. But Barty would make no mistake on her fifth match point of the tilt, ending a rally with a forehand crosscourt winner to overcome the Grand Slam main draw debutante.