PARIS, France - No.31 seed Petra Martic broke her Grand Slam fourth-round duck in battling fashion at Roland Garros, coming from a set down and a break down in both second and third sets to overcome Kaia Kanepi 5-7, 6-2, 6-4 in two hours and 12 minutes. 

The result sets up a rematch in the next round of April's Istanbul final against another first-time quarterfinalist, Czech teenager Marketa Vondrousova. Martic, who also becomes the first Croatian quarterfinalist in Paris since Iva Majoli's title run in 1997, overturned past form at this stage in dramatic fashion. The 28-year-old had lost all four previous major fourth rounds she had contested, including twice here in 2012 and 2017. By contrast, Kanepi had won six of her eight, with her only losses in the last 16 of a Grand Slam coming at the US Open in 2014 and 2018 to Serena Williams.

"It was tough mentally for me today," admitted Martic afterwards. "Especially because I was stopped four times before in the fourth round... I was doubting whether I was ever going to get that fourth round [win]. Two years ago I was two points away. Didn't happen. Today it played a role in my mind. It was not always easy to focus on my game, but I really just tried to fight as hard as I could, and thank God, I finally made it.

"Emotions played a big role today. She also wanted it badly, you could see."

The result is also a vindication of Martic's decision to hire Sandra Zaniewska as her coach - a rare example in tennis of a coach being younger than her charge. "When I started working with her, everybody was doubting my decision," recalled Martic. "People underestimated it, people even laughed at it, said I did a crazy thing, what am I doing? I'm not serious about my career because she's so young and inexperienced. But I always knew, I heard this girl talking about tennis and I knew she knows what she's doing... It was a pretty bold move, and I was a bit shaky at the beginning, because I also wanted to prove that I did the right thing.

"But after a month or two, I really just let go of this thought and I just kept on playing my tennis, and I was just improving from [one] week to another, and here I am. I think there is no better reward."

Zaniewska has been particularly crucial in helping Martic deal with the new mental challenges that constantly emerge in tennis - specifically, this week, with regards to the pressure of success. "I felt a bit of pressure just because I played so well on clay, and I had so many wins," admitted Martic. "I would lie if I said I didn't have ambitions to go far here. New things pop up in your head and she really helps me kind of get over all those things. We talk every single day about them, especially before the matches."

Read more: 'I believed my best years were ahead' - Comeback queen Martic enjoys Istanbul triumph

Martic and Kanepi have been fixtures on the WTA Tour for the best part of a decade, though both have been forced to take hiatuses at various times in careers beset by injury - but somehow had never played each other before today. Martic, with less success at this juncture of a major, seemed nervier from the outset, committing nine unforced errors in the first three games alone - but soon settled, getting her forehand under control to nab the first break.

The World No.88 hit back immediately, though, firing consecutive down-the-line winners off each wing to break back. In a tightly contested remainder of the set, the next break point to hove into view would be a set point as Martic served at 5-6 - and although the Istanbul champion showed bravery in essaying a serve-and-volley play, Kanepi would reset the point with a pinpoint lob and eventually sneak the set as Martic found the net with a backhand.

However, the second act saw Martic demonstrating exactly why she has tallied the highest number of claycourt victories on the WTA Tour this year, with her 14-2 record coming into this match including a maiden title in Istanbul in Turkey. Despite losing the first eight points of the set in a flurry of errors and double faults, Martic struck back to reel off six consecutive games to level the score.

The Charleston semifinalist's dropshot in particular worked wonders, with a leaping iteration of it drawing vocal appreciation from the crowd. But Martic was unable to sustain her purple patch as the decider got under way; with her forehand letting her down, it was instead 33-year-old Kanepi who upped the pace from the baseline to take a 2-0 lead once again.

In full flow and on the brink of running away with the match, though, the former World No.15 would squander a 40-0 lead for 3-0, committing a series of errors to drop serve twice and put Martic in the driver's seat.

As momentum swung from one player to another, the contest became ever more compelling. The Croat could not press home her advantage: tentative net play enabled Kanepi to smack a backhand pass to break back, and the Estonian seemed to have regained the upper hand when she staved off three break points to hold for 4-3, displaying some wondrous defence as Martic hauled her up and down the court with dropshots and lobs to come through that game.

But as the match reached its climax, it was Martic who found the necessary magic. The eighth game was a riveting mini-contest of its own: a wobbling Martic, who served consecutive double faults in this game, found herself facing break point to fall behind 3-5 on four occasions. But each time, she would find the serves and groundstrokes she needed to cling on - and ultimately hold for 4-4.

As though liberated by that hold, the dénouement would find Martic reaching new heights. Two marvelous defensive points paved the way to a love break of the Kanepi serve; and stepping up to the line to end her fourth-round losing streak, there were no signs of nerves. Instead, there was another highlight reel shot in a reflexed lob to reach match point, and delight as a Kanepi backhand found the net to seal a belated milestone for Martic.

"I feel like I managed to run out a few long rallies, gave me some confidence and I felt she got discouraged," recalled Martic of the closing stages. "In the end, I just managed to stay calm at my last service game, and I think that those few points in the third set made a difference."

Up next is a familiar foe in Marketa Vondrousova, whom Martic has beaten all four times they have played - twice this year, including in the Istanbul final in April. "I know her pretty well," Martic smiled. "I think she's a great player, great person. I'm really looking forward to this match. I think it's going to be a fun one. She's also got a few tricks in her game, but I like that!"