Ukrainian professional tennis player Marta Kostyuk just shocked the tennis world as she pulled off an upset win to carve her way to the 2026 French Open quarterfinals. The upset extended her clay-court winning streak to 16 matches as she continues a dominant 2026 campaign. 

One of the biggest outcomes of the tournament came when Kostyuk defeated 4x French Open champion Iga Swiatek 7-5, 6-1 in the fourth round in Paris on Sunday, May 31, 2026.

The win also pushed her into a maiden French Open quarterfinal. Most importantly, it eliminated the former Roland Garros champion.

Swiatek entered the match with a 43-3 career record at the tournament. Swiatek had won all three previous games against Kostyuk without dropping a single set. 

The first set was an intense battle from the baseline. Swiatek was leading 5-4. However, Kostyuk bounced back after a series of double faults from Swiatek. Kostyuk then closed out the opening set 7-5. 

Kostyuk then took control of the court.

Swiatek managed to grab an early break in the second set, but she could not hold the momentum. Kostyuk ran away with the win in the final stretch of games. She converted 6 break points and capitalized on 39 unforced errors from her opponent.

Kostyuk remains the only undefeated player on the WTA tour on this surface in 2026. Her streak started after she returned from an injury break earlier this year. She won titles in Rouen and Madrid along the way. 

But physical skill alone does not explain a 16-match winning streak against the world's best. A mindset change behind the scenes explains her recent dominance.

The Mental Shift Driving Marta Kostyuk's Breakthrough

Near the end of 2025, Kostyuk considered stepping away from tennis altogether. She worked with a therapist to separate her self-worth from her game results. This helped her to enter 2026 with a fresh perspective.

Even after beating a legendary clay-court player, she focused on the experience rather than the achievement. She made it clear that her goals have shifted entirely. She told the press that she tries not to focus on winning or losing because she no longer plays tennis just to win. 

“Even if I go through some difficult moments, some negative emotions, I realize how colourful my life is,” she said, per a May 31 report by Charlie Eccleshare of The Athletic.

That calm approach was obvious when she handled momentum swings without panicking. 

Next up is a quarterfinal against fellow Ukrainian Elina Svitolina. The winner of this match will become the first Ukrainian woman to reach a French Open semifinal in the Open Era. 

Do you think this new mindset is enough to carry Marta Kostyuk all the way to the trophy? Let us know in the comments.

Read more at Her Sports Nation. 

Written by

Utsav Sinha

Edited by

Surjo Ray