Sebastian Korda, son of 1998 Australian Open champ Petr, reaches first Slam quarterfinal

WATCH: Elena Rybakina defeats Iga Swiatek in the 2023 Australian Open fourth round

MELBOURNE, Australia (AP) — This was not a smooth ride for Sebastian Korda at the Australian Open on Sunday. An early deficit against a higher-seeded opponent. Some so-so serving. An up-and-down fifth-set tiebreaker filled with mistakes by both players.

At the end—the very end—it was Korda, a 22-year-old American, who earned a spot in his first Grand Slam quarterfinal by edging No. 10 Hubert Hurkacz 3-6, 6-3, 6-2, 1-6, 7-6 (10-7).

"Just tried to stay as calm as I possibly could," said Korda, whose father, Petr, won the 1998 championship in Australia. "I'm very happy with the way I just stayed down, kept going through it, and the outcome was great."

Korda's mother was a professional tennis player, too, and his two older sisters play pro golf.

This victory followed up a third-round win for Korda against 2021 U.S. Open champion Daniil Medvedev, the runner-up at Melbourne Park each of the past two years.

The 29th-seeded Korda will face 18th-seeded Karen Khachanov for a spot in the semifinals.

Korda was one of four American men to get to the fourth round, along with Ben Shelton, J.J. Wolf and Tommy Paul, the most for the country in Australia since four made it in 2004. That quartet included Andre Agassi, who serves as a mentor to Korda these days.

Khachanov, who was a semifinalist at last year's U.S. Open, eliminated Yoshihito Nishioka 6-0, 6-0, 7-6 (4) earlier Sunday.

The men's fourth-rounders also scheduled for Sunday: No. 3 Stefanos Tsitsipas vs. No. 15 Jannik Sinner, and No. 6 Felix Auger-Aliassime vs. unseeded Jiri Lehecka.

Korda vs. Hurkacz came down to the first-to-10, win-by-2 tiebreaker now used at all major tournaments in the fifth sets of men's matches and third sets of women's. Both players appeared to be tight, neither was able to muster much in the way of winners, and the scoreline swings were as wild as can be.

Hurkacz, whose victory over Roger Federer at Wimbledon in 2021 was the 20-time Grand Slam champion's final singles match, went ahead 3-1. Then Korda took six consecutive points to lead 7-3. And then Hurkacz grabbed four in a row to tie it at 7-all.

Right then, though, is where Korda emerged with some of his best deliveries of the day.

An overhead that ended a 20-stroke exchange—and led to Hurkacz knocking over a serve-speed readout display at the back of the court—made it 8-7. A 117 mph (188 kph) service winner made it 9-7. And a down-the-line backhand passing winner to cap a 27-shot point finished things off.

"There was plenty of times where I could have just completely lost it. I lost it a little bit a couple points," said Korda, whose coach, Radek Stepanek, repeatedly hopped out of his seat in the stands Sunday. "But I just stuck with it, tried to be as positive as I can. Especially toward the whole fifth, that was my only goal."