PARIS, France - Former French Open champion Jelena Ostapenko soared into the third round of Roland Garros for the first time since winning the title in 2017, playing pitch perfect tennis to upset former World No.1 Karolina Pliskova, 6-4, 6-2.

"I think I was playing good today," Ostapenko said in her post-match press conference. "I knew it was going to be a tough match, so I was trying to be very focused all match, playing my game. I tried to keep the ball in play to make sure I'm not missing and making too many unforced errors, but when I had the chance I was going for it.

"Obviously I knew she's a great player so it's going to be a tough match, but I think I played well today."

In the years since her epic win over future champion Simona Halep, Ostapenko has seen plenty of ups and downs but it was only up against the No.2 seed, serving out the win in 69 minutes beneath the Court Philippe-Chatrier roof.

Facing off for a sixth time in their careers, Ostapenko and Pliskova have played their share of epics, most recently at the China Open, where the Latvian survived a thrilling three-setter last fall. Their last clay court clash went Pliskova's way, as the three-time Ace Leader ousted the then-reigning Roland Garros champion en route to the 2018 Porsche Tennis Grand Prix title.

Looking below her best during the post-lockdown North York swing, Pliskova showed vast improvement at the Internazionali BNL d'Italia, where she came within one match of defending her title, only to incur a left thigh injury that forced to retire in the championship match and send her onto the terre battue beneath an injury cloud.

A former World No.5, Ostapenko was unseeded in Paris after an uneven 2020, but was impressive in her first round dismissal of American Madison Brengle, while Pliskova needed three sets to defeat Egyptian qualifer Mayar Sherif.

"I'm sure I could do much better," Pliskova said after the match. "I know that she can be tough if she's playing well, but I think everything started with me. I was definitely not playing great. I think maybe same level as the match before but of course she's a much better player."

Emerging from an early exchange of breaks with the early advantage, the 23-year-old - in Paris with new coach Thomas Hogstedt - found herself initially pegged back by Pliskova, but broke straight back with some relentless returning of her own, striking back-to-back forehand return winners on her way to a 5-3 lead.

The No.2 seed put the pressure on Ostapenko with a love service hold to stay in the set, and Ostapenko responded with a similarly straightforward hold herself, converting her first set point with a service winner and ending the set with an even 12 winners to 12 unforced errors - compared to Pliskova's 5-13 differential.

"I knew I have to return well today because she obviously has one of the best serves on tour," Ostapenko said. "I think I was returning very well today. Also, I had to hold my serve, which I did pretty good, just once in the first set I didn't hold my serve.

"I knew I have to do these things well and just try to maybe put as many balls as I can back and to make the points longer and if I have a chance just to go for it. Also, to use some dropshots, because it's a very good shot in these conditions."

Opening the second set with an audacious drop shot and a thunderous forehand winner, the former Wimbledon semifinalist nabbed another break and won a third straight game by overpowering Pliskova on the forehand side.

The former World No.1 saved a break point in the fifth game and was soon behind two more as Ostapenko closed in on victory, moving to 15-40 with another drop shot winner. Another scintillating forehand return clinched the double break for Ostapenko, who would serve for her first French Open third round since winning the title in 2017.

"I think I'm similar as I was playing then. It's hard to compare because that was three years ago and I was fearless, nobody really knew me but now players got to know me more. Obviously they know me already. They know how I can play. They know how to play probably against me. So I try to prepare very well for every match."

Showing some nerves at the finish line, Ostapenko nonetheless held firm, converting her third match point to make it over the finish line.

In all, the Latvian struck a formidable 27 winners to just 19 unforced errors, converting five of nine break point chances and winning over half of points played on return while posting stellar serving stats, winning 73% of her first serve points.

"I think now I'm in a good form, and obviously these two matches I played really well, as well as a couple of matches in Strasbourg. Slowly I'm getting back in this form and playing some matches in this rhythm again."

Up next for the former champion is 2015 junior winner Paula Badosa, who upset 2018 runner-up Sloane Stephens to reach the third round of a Grand Slam tournament for the first time.

"Of course I want to achieve more and I want to be back in Top 5, Top 10. Step by step. That's what I'm working on, my consistency, while still being aggressive player, I think it can bring me a lot of wins but consistency probably in my game is the key."

2020 Roland Garros highlights: Ostapenko overwhelms Pliskova in upset