Karen Khachanov ousts John Isner, last U.S. man at French Open

— -- Two weeks past his 21st birthday, unseeded Karen Khachanov of Russia became the youngest man to reach the French Open's fourth round since 2009, beating 21st-seeded American John Isner 7-6 (1), 6-3, 6-7 (5), 7-6 (3).

Meanwhile,? Rafael Nadal eased past fellow Spaniard and 17th-seeded Roberto Bautista Agut 6-1, 6-2, 6-2 to reach the quarterfinals, while? Richard Gasquet retired from his all-French third-round match against Gael Monfils?after getting treatment on his right thigh.

Isner was the last U.S. man in the draw of 11 who entered the tournament. Khachanov is playing at Roland Garros for the first time. It is only the third major of his career.

The match was suspended a night earlier after the first set because of rain.

Despite hitting eight double faults, Khachanov won all 23 games he served against Inser, saving four break points. Khachanov converted 1 of 6 break points on Isner's serve, but that was enough.

The rain delay suited Kei Nishikori as he recovered to beat Hyeon Chung 7-5, 6-4, 6-7 (4), 0-6, 6-4 when their third round match resumed.

The eighth-seeded Nishikori was leading 7-5, 6-4, 6-7 (4), 0-3 when rain stopped play Saturday, but was clearly struggling with a wrist injury and had also had treatment on his back as the 21-year-old Chung rallied.

Chung, who is ranked 67th, had never beaten a top-10 player in six attempts but leveled when play resumed, keeping alive his bid to become the first South Korean to reach the fourth round at Roland Garros.

Nishikori broke early in the fifth set and was serving for the match when Chung broke back, but the Japanese player sealed the result when his opponent double faulted.

It was the first time in the Open era that two Asian men had met as late as the third round in a Grand Slam tournament.

The 24th-seeded Gasquet stopped playing while trailing 4-3 in the third set. The players split the first two sets.

Before the start of the third, Gasquet had a trainer work on his upper right leg. Gasquet got a massage and then his thigh was taped up.

The 15th-seeded Monfils moved into the fourth round at the French Open for the seventh time. His best showing in Paris was a semifinal run in 2008.

Nadal won in less than two hours. Nadal is through to his 11th at Roland Garros -- equaling Roger Federer's Open era record.

The 31-year-old Nadal is seeking his 10th French Open title and 15th Grand Slam title.

His last major came at Roland Garros in 2014. His opponent in the last eight will be Spaniard? Pablo Carreno Busta beat fifth-seeded Milos Raonic of Canada?4-6, 7-6 (2), 6-7 (6), 6-4, 8-6.

Carreno Busta reached his first Grand Slam quarterfinal the hard way, wasting six match points through a combination of unforced errors and big winners from Raonic.

He wasted three of them serving at 5-4 up, and three more when serving at 7-6.

He finally won with a forehand volley at the net, with Raonic near the back of the court.

The Associated Press contributed to this report.