PARIS, France - Katerina Siniakova sprung the biggest upset of Roland Garros 2019, eliminating No.1 seed Naomi Osaka 6-4, 6-2 in a third-round contest between two top-ranked players.

It was the doubles World No.1 who got the better of the singles World No.1 with a multifaceted game and superior clutch play to notch up her fifth Top 10 win - but first over a Top 3 player. The last time a doubles World No.1 had beaten a singles World No.1 on the singles court was the 1987 US Open final, when Martina Navratilova defeated Stefanie Graf 7-6(4), 6-1.

Siniakova's doubles experience had been key to closing out the win, she said afterwards. "I had some matches on the biggest courts here in doubles. So the atmosphere is much different than on a smaller court. So in this case, it helped me [with] what you can expect. And... for sure it was helping my game, and even the mentality."

Osaka, who had posted two astonishing recoveries already to make this stage - 0-6, 7-6(4), 6-1 over Anna Karolina Schmiedlova after being two points from losing on multiple occasions, and  4-6, 7-5, 6-3 over former World No.1 Victoria Azarenka from a set and a break down - was unable to summon up another comeback against a dynamic and amped-up Siniakova.

In a change from her first two rounds, the US Open and Australian Open champion came out sharp, firing backhand winners at will to immediately test the Siniakova serve. But the tenacious Czech would consistently find her finest shots when under the cosh, unleashing on a forehand to save break point in her first service game and then conjuring a dropshot and a service winner to save two more in the sixth game.

Osaka would come to rue those missed chances. With Siniakova finding her range and extending the rallies, the defending doubles champion carved out two break points of her own at 4-4. Spectacular Osaka forehand winners saved both - but the 21-year-old sent another forehand wide on the third.
Siniakova had also survived a marathon second-rounder, upsetting No.29 seed Maria Sakkari 7-6(5), 6-7(8), 6-3 in a three-hour, 10-minute rollercoaster - the fifth-longest match of the season - in which no lead had been safe. That experience seemed to have boosted the World No.42's fortitude: despite falling behind 0-40 as she served for the set, Siniakova's dropshot, forehand and serve all came through for her as she repelled four break points to take the lead.

"It was brave, but I believe in my dropshot," Siniakova smiled afterwards of the shot that had won her multiple crucial points. "I think it's really good. It was one shot I could use against her... Actually, it was really tough to finish the set, and I was really happy I fight back and I finish it."

Osaka's ratio of winners to unforced errors had been 14 to 16 in the first set, but the start of the second set saw the balance tipping alarmingly towards the latter - particularly in the face of some indefatigable retrieving on Siniakova's part - which ultimately tallied 38. Four netted groundstrokes in the fifth game put her a break down, and Siniakova once again demonstrated her clutch mentality by squeezing out a tight hold to consolidate.

Scampering around the court, offering a meagre six unforced errors of her own in the second set and varying both angle and spin, Siniakova proved to be a brick wall that Osaka was unable to hit through. Errors continued to pile up for the Japanese player: a third double fault put her a double break down. Osaka mustered little resistance as Siniakova served for a career-best singles win, and a forehand over the line sealed victory after one hour and 17 minutes.

Into the second week of a Grand Slam in singles for the first time, Siniakova will now face either No.14 seed Madison Keys or qualifier Anna Blinkova in a bid to keep her run going.