EASTBOURNE, Great Britain - Former French Open champion Jelena Ostapenko shook off a slow start to dispatch 2017 US Open winner Sloane Stephens, 1-6, 6-0, 6-3, and reach the Round of 16 at Nature Valley International.

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"I've had five tough matches and four wins out of five. I'm feeling really good because I was struggling a little bit at the beginning of the season, being injured last year. It was very tough for me, but I think I'm getting in form, and getting better," Ostapenko said during her on-court interview.

In a rematch of the 2018 Miami Open final, Ostapenko went on a streak of 11 of 12 games before ultimately treating the Court 3 crowd to a tense ending as she secured her first Top 10 win of 2019 after 90 minutes. 

The Latvian has enjoyed a grass court resurgence after struggling through the start of the season with injuries and inconsistency, reaching the Nature Valley Classic quarterfinals last week with a win over Roland Garros semifinalist Johanna Konta en route.

Stephens, by contrast, was playing her first match of the grass court season after reaching the quarterfinals in Paris, but the 2013 Wimbledon quarterfinalist nonetheless raced through the opening set as Ostapenko was unable to find her range.

"The first set was really tough for me because I couldn't really get a rhythm with my game," she explained after the match. "I was making many unforced errors, but in the second and third sets, I was trying to be more aggressive, and I think I was more in the game, more focused, and more consistent. Playing aggressive brings me good results."

Though Ostapenko struck 20 unforced errors - to just one winner - and eight double faults in the first seven games of the match, the former World No.5 and 2018 Wimbledon semifinalist soon caught fire in the second, blanking Stephens to level the match - coming out victorious in a titanic fourth game that likely decided the set.

Ostapenko continued that form in the final set as she took a 5-1 lead, but there were shades of her loss to Petra Martic in Birmingham at the finish line as Stephens began working her way into the match, getting one of the two breaks back and saving two match points in the final game.

The unseeded 22-year-old made no mistake on her third opportunity and booked a third round encounter against rising Russian Ekaterina Alexandrova, who survived a tough test from Mallorca Open runner-up Belinda Bencic.

"I've played Bencic a few times, and I think she's in good form, seeing as she made a final last week. I'm going to focus more on myself because I love playing on grass and this surface suits my game well."

In all, Ostapenko ended the match with 22 winners to 40 unforced errors - though half came in the first set alone - four aces to 14 double faults, and a seven of 12 break point conversion rate. Despite Stephens' strong start, her serve was soon under fire from Ostapenko, who won the majority of return points in the final two sets.

"I think I'm getting my confidence back, and grass can only help me because it's hard to move on this surface and my shots are more effective."