MELBOURNE — 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 taking the last trio of points to edge No. 10 Hubert Hurkacz 3-6, 6-3, 6-2, 1-6, 7-6 (10-7).

“Those are the toughest points to win … those last three there,” said Korda, whose father, Petr, won the 1998 championship in Australia. “They’re brutal in a way.”

The younger Korda has made it a point to reach out and tap signs marking the titles won by his dad and by mentor Andre Agassi in the hallway leading to the court in Rod Laver Arena.

“Every single time I walk by, I always give … a little fist bump,” Korda said. “Kind of makes me feel like they’re with me, in a way. I always know that they’re watching. They’re both very special for me. They helped me a ton.”

Korda’s mother was a professional tennis player, too, and his two older sisters play pro golf. They’ve been following the guy they call “Sebi,” via TV from the United States during the Australian Open, despite the 16-hour time difference between the East Coast and Melbourne.

“I just got off the phone with them,” Korda said about his parents. “They’re going to try to go to bed.”

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. The other quarterfinal on the top half of the bracket will feature unseeded Jiri Lehecka against No. 3 Stefanos Tsitsipas, who beat No. 15 Jannik Sinner 6-4, 6-4, 3-6, 4-6, 6-3 in 4 hours.

“I felt like I spent an entire century on this court, playing tennis. It felt so long,” said Tsitsipas, who also beat Skinner in Australia a year ago. “What a great night. That was superb.”

Korda was one of four American men to get to the fourth round, along with Ben Shelton, J.J. Wolf and Tommy Paul — who all play Monday — the most for the country in Australia since four made it in 2004.

“It’s awesome,” Korda said. “We’ve got a great group coming up. I think we can do some special things in the next couple years.”

Khachanov, a semifinalist at last year’s U.S. Open, eliminated Yoshihito Nishioka 6-0, 6-0, 7-6 (4) earlier Sunday. Lehecka arrived in Australia with an 0-4 career record in Grand Slam matches, but he is now in the quarterfinals after beating No. 6 Felix Auger-Aliassime 4-6, 6-3, 7-6 (2), 7-6 (3).

“I’m sure we will see a lot of him in the future,” Auger-Aliassime said.

While Novak Djokovic, whose fourth-round match against Australia’s Alex di Minaur is Monday, is the lone man left with a Grand Slam title — and he’s got 21 of them, nine at Melbourne Park — Tsitsipas is the only other past major finalist still around.

He was the runner-up to Djokovic at Roland Garros in 2021 and has reached the semifinals in Australia three times.

Tsitsipas, a 24-year-old from Greece, looked terrific against Sinner for two sets Sunday night, something less than terrific for two sets, then surged to victory by breaking to lead 4-2 in the fifth.

“Stayed really calm, just like Mr. Rod Laver used to do in his day,” said Tsitsipas, shouting out the stadium’s namesake, who was in attendance.

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.”