No.4 seed Karolina Pliskova and No.11 seed Maria Sakkari both took the scenic route into the last 16 of the Omnium Banque Nationale.
Pliskova was two points from defeat in her deciding set against Donna Vekic, but survived 4-6, 6-3, 7-6(2) in two hour and 35 minutes. Preceding her on Court Rogers, Sakkari had been unable to close out a break lead in the second set against Veronika Kudermetova, but overturned a break deficit in the third to win 6-4, 5-7, 6-4 in two hours and 38 minutes.
Former World No.1 Pliskova had already beaten Vekic twice in the past three months, on clay at Roland Garros and on grass en route to her second Grand Slam final at Wimbledon. Indeed, the Czech had won their five previous encounters stretching back to Vekic's sole win in the series, in 2012 US Open qualifying.
This match would be their closest, though, as Pliskova kept opening the door for Vekic when seemingly in control. After a slow start put her down an early break, the 29-year-old unleashed some superb forehands to level at 3-3 - only to throw in a sloppy game at 4-4 and, on Vekic's first set point, net a makeable dropshot chase.
Pliskova was more authoritative as she took the second set and built a 4-2 lead in the third, most notably increasing her first serve percentage from 45% in the first set to 64% in the second. But one of her nine double faults enabled Vekic to level at 4-4 and force Pliskova to fight back from the brink of defeat - which she did in style. Serving at 4-5, 30-30, she found one of her 15 aces, and proceeded to dominate the ensuing tiebreak.
In total, Pliskova tallied a perfectly balanced 46 winners to 46 unforced errors, while Vekic was plagued by 11 double faults - which frequently came at inopportune times - and finished with 26 winners to 43 unforced errors.
Pliskova will next face Amanda Anisimova, who came through a battle of qualifiers over Oceane Dodin 6-3, 6-3. The result marks the third time the American has won consecutive WTA main draw matches this year, following her quarterfinal runs in Parma and Bad Homburg.
Sakkari also managed to survive an arduous contest decided more by mistakes than winners. The Greek committed 45 unforced errors to 22 winners, and landed only 49% of her first serves. But Kudermetova's numbers were similar, 48 unforced errors to 24 winners, and the key for Sakkari was managing to play better tennis on the most important points.
In particular, Kudermetova struggled to hold on to her leads. In the first set, the Russian came from an early break down and came out on top of a knife-edge four-deuce tussle, saving three break points, to lead 4-3. But she would swiftly become error-strewn, and instead it was Sakkari who reeled off five games in a row to take a 2-0 second-set lead.
Kudermetova once again found her most confident tennis when behind, and hit a spell of formidable serving for the remainder of the set. Sakkari, who had just about clung on for most of it, was unable to do so again at 5-6 in the face of Kudermetova's irresistible ball-striking.
The Roland Garros semifinalist, furious with herself for losing the set on a long forehand, received a point penalty for ball abuse to start the deciding set, and Kudermetova maintained her ascendancy to break for 2-0 with a brilliant angled backhand return.
But a dropshot wide handed the lead back immediately, and despite another edgy mid-set exchange of breaks, Kudermetova never recovered her control. Errant backhands conceded her serve for Sakkari to lead 4-3, and the World No.18 managed to pull out her best deliveries to save two break-back points en route to serving out the match.
Next up for Sakkari is No.8 seed Victoria Azarenka, a rematch of last year's Ostrava semifinal, won by the Belarusian 6-1, 6-3.
Elsewhere, Sara Sorribes Tormo won a match of extreme stylistic contrasts, with her superb defence and ability to strike passing shots on the run overcoming Liudmila Samsonova 6-4, 6-3. The Russian's all-out aggression garnered her a number of highlight reel points, particularly impressing at net, but was not enough to hit through Sorribes Tormo on a consistent basis.