Four-time champion Iga Swiatek was knocked out of the French Open on her 25th birthday, losing her fourth-round match in straight sets to in-form Marta Kostyuk.
Polish third seed Swiatek was plagued by inconsistencies as Ukrainian 15th seed Kostyuk won 7-5 6-1 on Court Philippe Chatrier.
Swiatek is nicknamed the "Queen of Clay" having won four titles at Roland Garros, but has not won a title on the surface since her most recent triumph in Paris in 2024.
The six-time Grand Slam champion, who will start the defence of her Wimbledon title at the end of June, is yet to win a a tournament in 2026 and said in her post-match press conference that it "wasn't a good day in the office".
In contrast, Kostyuk entered the French Open undefeated on clay in 2026 having won titles at the Madrid Open earlier this month and the Rouen Open in April.
Kostyuk said: "I feel like I've given myself more space to just create something, to challenge my opponents.
"The most important thing I've been doing this whole time is really just trying to enjoy it. I woke up in the morning and all I thought about was what an unbelievable day I have to live today, playing on Chatrier against Iga. There's nothing I could do today other than this."
Kostyuk will play fellow Ukrainian Elina Svitolina in the quarter-finals after the seventh seed's 4-6 6-4 6-0 win over Switzerland's Belinda Bencic.
There was little to separate the duo in the first set as they twice traded breaks, before Kostyuk took control at the end.
The brilliance of Swiatek's strokeplay was on display when returning against Kostyuk but unforced errors hampered her serve as two double faults gave the Ukrainian the advantage before she won the opening set with a fine backhand winner.
Kostyuk had not taken a set off Swiatek in their three previous tour-level meetings and the 23-year-old's confidence grew as she tightened her grip on the match.
Her powerful groundstrokes continued to wear Swiatek down as she ran away with the second set to reach the last eight at Roland Garros for the first time, while it is the first time that Swiatek has failed to reach the quarter-final at the French Open since her debut in 2019.
Swiatek's defeat comes amid a spell of big names exiting the men's and women's draws at Roland Garros.
Men's world number one Jannik Sinner, 24-times Grand Slam winner Novak Djokovic and defending women's champion Coco Gauff have all gone out of the event in recent days.
