No.17 seed Maria Sakkari of Greece claimed a hard-fought victory over a frequent rival to reach the fourth round of Roland Garros for the first time in her career, as she edged past No.14 seed Elise Mertens of Belgium, 7-5, 6-7(2), 6-2 in a nearly three-hour contest.

Sakkari and Mertens had faced off numerous times at all levels of professional tennis dating back to 2014, from ITF Challengers to, now, Grand Slam main draws. Mertens held the slight 4-3 edge coming into their match, but Sakkari had won their only previous match on clay.

The Greek came through again on Court Simonne Mathieu to tie up their head-to-head at four wins apiece. The Greek fired an astounding 53 winners (22 more than Mertens) to collect victory and reach the second week of a major for the third time in her career.

"I think it was one of my best matches I have played in a long time, this year as well," Sakkari said, in her post-match press conference. "Elise played extremely well, I think. She never gave up. I think I just played probably the right way when I had to. I gave myself a better chance today. I just took the chances, especially in the third set."

A grueling first game set the tone for the opening frame, as the pair went back and forth before Mertens converted her fifth break point of that tussle. Sakkari eventually got back level at 2-2, and the battle, replete with all-court rallies, was on.

After a hold for 6-5, Sakkari found a key opportunity in the next game, when Mertens double-faulted away a game point. Sakkari then fired a forehand pass crosscourt to reach set point, and the Greek converted that chance after a wide error by Mertens.

Following the 68-minute first set, Sakkari twice fought her way back from a break down in the second set, and was two points away from a straight-set win at 5-4, 30-30. But Mertens continued to press, and the Belgian slammed a backhand winner to hold for 6-6 and move the set into a tiebreak.

In the breaker, Sakkari was undone by two double faults as Mertens quickly zoomed ahead 4-1. A backhand error by the Greek gave Mertens double set point at 6-1, and on her second chance, Mertens took another protracted set after coming out on top in one more tough rally.

However, Sakkari turned the match back around in her favor, converting her fourth break point of a pivotal first game to go up an early break in the decider. A dropshot winner on break point gave Sakkari an insurance break to lead 4-1, and the Greek cruised home from there.

"Going a double-break up was very -- how can I say it -- stress relief," Sakkari said, regarding the final set.

"It's tough when you lose a second set that way, and then you manage to just get everything back on the right way, and just find a way to win," Sakkari added.

Sakkari will now take on last year's finalist Sofia Kenin in the round of 16. Kenin also got through a tough three-set tussle when she overcame her fellow American Jessica Pegula earlier on Saturday.

"[Kenin] played the final here last year, so she's playing good here, for sure," Sakkari said. "You know, you don't get easy opponents in these rounds of a Slam."

No.24 seed Coco Gauff of the United States also made it into the fourth round at Roland Garros for the very first time, after her compatriot, No.13 seed Jennifer Brady, had to retire due to a foot injury after losing the first set of their clash 6-1.

"It's unfortunate because I have known Jenny very well, and she's such a nice person," Gauff told the press. "If you ask every player on tour, no one is going to say anything bad about her because she's always laughing and joking around. So I just hope that by the time Wimbledon comes she'll be healed up and ready to compete at 100 percent again."

Reigning Australian Open finalist Brady had won their previous clash in last year's Lexington semifinals, but Gauff had been on an extreme rise on clay. 17-year-old Gauff came into Paris following a superb clay-court season, winning her second career WTA singles title (as well as the doubles title) in Parma and making the semifinals in Rome.

Gauff's run was continuing with aplomb in the opening stages of her match against Brady, as she won all 12 of her first-service points and never faced a break point in the first set. Brady, though, was struggling with discomfort, retiring directly after the 23-minute stanza.

"I actually was considering not even playing here," Brady said, explaining that she had been struggling with plantar fasciitis and a bone bruise since Rome last month. "I wasn't going to step out there unless I could finish the match in the first round. Happy that I was able to get a couple of matches in.

"Then today, I woke up and it was, you know, just worse. I couldn't really play my game. I was about 20 percent moving. So unfortunate."

Despite the injury retirement, it counts as a 24th match-win in 2021 for Gauff, who has the fourth-most match-wins on tour this season (surpassed only by Ashleigh Barty, Aryna Sabalenka, and Veronika Kudermetova). One more win will propel Gauff into her first-ever Grand Slam quarterfinal.

To do that, Gauff will next have to defeat the player seeded one spot behind her, and someone who has nearly as many victories as she does in 2021: No.25 seed Ons Jabeur of Tunisia. Jabeur shook off a rough first set to eventually storm past Magda Linette of Poland, 3-6, 6-0, 6-1.

Jabeur and Linette had split their two previous meetings, and after the first set, Linette was primed for an upset to take the lead in their rivalry. But Jabeur executed the comeback win after an hour and a half, picking up her 23rd match-win of the season.

"I think I was kind of tight a little bit at the beginning, so I wasn't actually playing my game," Jabeur said in her post-match press conference. "But I'm very proud of myself that at 5-3, I tried to come back, and I accepted the way she was playing good. Actually, she was playing very correctly and she was putting pressure on me.

"I wasn't playing amazing, so in the second set, I changed the way I was thinking. I was like, 'Okay, I'm just going to play my game. I'm just going to release a little bit of tension and just be myself on the court.' And that's what I did, and it helped pretty well."

Linette, who advanced when World No.1 Ashleigh Barty retired from their match in the second round, out-winnered Jabeur by ten to eight in the opening set. However, the Tunisian completely turned that around in the second set, firing ten winners of her own while allowing Linette none during that timeframe.

Jabeur continued her dominance in the third set, sweeping to a 5-0 lead before Linette fended off four match points in that game to get on the scoreboard for the first time since the first set. Jabeur was unfazed and held in the next game with ease, moving into the fourth round of Roland Garros for the second straight season.