No. 23 Nick Kyrgios of Australia outlasted No. 16 Karen Khachanov of Russia in an epic five-setter to reach the fourth round on Saturday at the Australian Open in Melbourne.

Kyrgios' reward for the 6-2, 7-6 (5), 6-7 (6), 6-7 (7), 7-6 (8) victory? He gets to face world No. 1 Rafael Nadal when the second week of play begins.

The 33-year-old Spaniard, who has won 19 Grand Slams including the 2009 Australian title, beat countryman Pablo Carreno-Busta 6-1, 6-2, 6-4 to advance.

Kyrgios declared the four-hour, 26-minute match against Khachanov "definitely one of the best wins of my career, I think."

"That was definitely one of the craziest matches I've ever been a part of. It was insane," Kyrgios said.

"Had a match point in the third, a match point in the fourth. Then 8/7 down, I had all the thoughts. I thought I was going to lose. I was thinking about everything. ... It was crazy."

Kyrgios is 3-4 against Nadal in his career and is excited to face the No. 1 seed on his home turf.

"I'm super excited, honestly. Playing one of the greatest tennis players on center court at your own Slam, it's pretty damn cool," said Kyrgios. "I've got a lot of time between now and then. Obviously, it's going to be another physical battle. Nothing comes easy with him. He had a relatively routine match today, so he's going to be feeling good. I'm looking forward to it. That's why you play."

Also advancing was fourth-seeded Russian Daniil Medvedev, who took an easy 6-4, 6-3, 6-2 win over Australia's Alexei Popyrin to earn a meeting with Stan Wawrinka of Switzerland. Popyrin was struggling with a left thigh injury.

Wawrinka, seeded 15th, advanced after American John Isner retired during their third-round match, trailing 6-4, 4-1.

No. 5 seed Dominic Thiem of Austria also made it to the fourth round, holding off No. 29 Taylor Fritz of the U.S. 6-2, 6-4, 6-7 (5), 6-4.

Thiem, who is trying to reach the quarterfinals here for the first time, will have to get through France's Gael Monfils.

Monfils, seeded No. 10, knocked off Latvia's Ernests Gulbis 7-6 (2), 6-4, 6-3 to earn a shot at Thiem, who has won all five of their career meetings.

Thiem said he's looking forward to the encounter.

"It's always fun to play against (Monfils)," said Thiem. "Such a great athlete. Such a great sportsman. We had fun and great encounters in the past. I expect similar."

No. 7 Alexander Zverev of Germany defeated Spain's Fernando Verdasco 6-2, 6-2, 6-4 to set up a meeting with No. 17 Andrey Rublev of Russia. Rublev rallied to eliminate 11th-seeded David Goffin of Belgium 2-6, 7-6 (3), 6-4, 7-6 (4).