Marta Kostyuk reached the quarterfinals at the French Open for the first time on Sunday (May 31, 2026) by taking out four-time champion Iga Swiatek 7-5, 6-1 and ruining her birthday.

Kostyuk, who is undefeated on clay this season, had lost their three previous matches and never taken a set against the former top-ranked player, who turned 25 on Sunday (May 31).

She defended extremely well, chasing Swiatek's shots all over the court, and also produced some stunning groundstroke winners while her rival was also undone by her own mistakes.

An intense baseline battle unfolded from the outset and Swiatek earned the first break when she overwhelmed Kostyuk after a long rally with a backhand winner.

Kostyuk broke back immediately, though, only to drop her serve again and hand Swiatek a 5-4 lead.

The Polish player showed signs of nerves as she double-faulted, shanked a forehand wide and then missed a volley at the net, allowing Kostyuk to level at 5-5. Swiatek hit two more double faults in the 12th game and the 15th-seeded Ukrainian player sealed the set with a backhand passing shot.

Swiatek then briefly left the court. Meanwhile, Kostyuk kept herself warm by stretching and hopping beside her chair, then received some applause as she did a few dance moves to the music playing in the stadium.

Following a first week marked by a suffocating heatwave, relief finally arrived in Paris on Sunday, with temperatures dropping to 21 degrees C (70 F) around midday.

When play resumed, Swiatek broke, but yet another double fault coupled with more unforced errors brought her opponent back at 1-1. Kostyuk then won the last five games.

Kostyuk had reached the fourth round at Roland Garros in 2021, losing to Swiatek.

The 15th-ranked Ukrainian is in a strong run of form and extended her winning streak on clay to 16 matches. Ahead of Roland Garros, she won in Madrid — the biggest title of her career — after she claimed another clay-court title in Rouen, France.

Swiatek has not won a title on clay since the 2024 French Open.