© Peter Staples/ATP World Tour

Kei Nishikori survives Hyeon Chung in five sets to reach the Roland Garros fourth round.

Nishikori Survives In Five, #NextGenATP Khachanov Upsets Isner

Japanese, Russian reach Round of 16

Eighth seed Kei Nishikori overcame an onslaught from #NextGenATP Korean Hyeon Chung, surviving after five sets and nearly four hours at Roland Garros.

The Japanese advanced to the Round of 16 with a rollercoaster 7-5, 6-4, 6-7(4), 0-6, 6-4 victory, firing a total 62 winners and seven aces, while converting six of 14 break chances. The win puts Nishikori into his sixth consecutive Grand Slam fourth round and third in a row on the Parisian clay. He improved to 16-6 in five-setters in his career.

The World No. 9 will look to match his best result here when he faces Fernando Verdasco on Monday. He leads their FedEx ATP Head2Head series 3-2, most recently prevailing at the ATP World Tour Masters 1000 event in Miami earlier this year. It is also a rematch of a third-round meeting at Roland Garros in 2016, won by Nishikori in five sets.

"I think the rain helped me a lot, because I was really down in the fourth set and mentally I wasn't ready," said Nishikori. "I knew I had to change something to beat him today, so I made some adjustments.

"I have to be a little more positive all the time during the match. But I think I'm feeling pretty good tennis-wise. And I try to be more positive and hopefully I can play another good one tomorrow."

One of three third-round encounters that were suspended due to rain on Saturday, Chung had surged to a 3-0 lead in the fourth set when the skies closed. But Nishikori battled back after play resumed on Sunday morning, responding strongly after conceding a fourth-set bagel and eventually advancing after three hours and 51 minutes.

#NextGenATP star Karen Khachanov was another player to have his taste of victory delayed by the inclement weather. The Russian upset 21st-seed John Isner 7-6(1), 6-3, 6-7(5), 7-6(3) on Court 1. 

Khachanov triumphed after exactly three hours, withstanding a baseline barrage from Isner that included 56 winners and 14 aces. The 21 year old saved all four break points faced and converted one of six to advance to the Round of 16 at a Grand Slam for the first time.

"I think it's in general the best result for me in a Grand Slam," said Khachanov. "So it's of course one of the biggest victories for me."

Making his tournament debut, Khachanov is the youngest man to reach the fourth round at Roland Garros since Marin Cilic did so at 20 years of age in 2009. He sets a date with top seed Andy Murray next, his first against a Top 5 opponent.

"I think it's going to be a good match and good experience for me," Khachanov added, referring to his impending clash against Murray. "I'm in the fourth round, and I will try to prepare and to do my best. I think that is what we are looking for, to play on the big arenas like here, centre court, and to play against the World No. 1. I'm really looking forward to it."

In the last third-round match awaiting conclusion from Saturday, Gael Monfils advanced when fellow Frenchman Richard Gasquet retired with a leg injury. Monfils was leading 7-6(5), 5-7, 4-3 when Gasquet called it quits. A semi-finalist in 2008, he will face third seed Stan Wawrinka next.

Go inside the tournament at RolandGarros.com.