Iga Świątek, the Polish world No. 1 and top seed in the Olympic tennis tournament, lost in the semifinals Thursday to China’s Zheng Qinwen, a massive upset in the women’s singles.

Świątek went down in straight sets, losing 6-2 7-5. The Pole has been a force at Roland Garros, the venue for the tennis at these Games, where she has won four French Open titles, including the last three in a row.

Świątek, who is the dominant force on clay in women’s tennis, entered the Paris Olympics as the overwhelming favorite to win gold.

“It’s truly indescribable how thrilled I am right now,” Zheng told the Olympics.com. “I defeated the world No. 1, the player who has been reigning champion at Roland Garros for years.

“This journey has not been easy. Additionally, having played over six hours on court in the past few days and spending around eight hours on court within three days, I felt like I was driven by sheer determination.

“I know that in a regular women’s match, my stamina might have run out after such extended play. But for some reason, today, my energy levels remained high throughout. I was certain that, even if the match went into the third set, I would fight until the last breath.

“Even if I had to play for another three hours for my country, I felt I could manage it. Beating the world No. 1 at the Olympic stage means a lot to me.”

Zheng jumped out to a dominant first set win, but five-time grand slam winner Świątek looked set to force a deciding tiebreaker with a roaring start to the second. But Zheng climbed all the way back from 0-4 down, sending the heavy favorite off to the bronze medal match.

It’s Świątek’s first loss at Roland Garros since 2021.

Zheng, the No. 6 seed, will face either Donna Vekić of Croatia or Slovakia’s Anna Karolína Schmiedlová in the gold medal match. The Chinese star was 0-6 against Świątek before this match

Świątek will face the loser of the match between Vekić and Schmiedlová in the bronze medal match.

Świątek had cruised through the tournament to this point, dropping one set in her previous four matches. At home on the clay, the Pole had been playing with a breezy confidence in her opening matches of the tournament until being pushed by Danielle Collins on Wednesday to a tiebreaker before the American was forced to retire.

But Zheng had given her trouble on this court in the past. In 2022, the now world No. 7 took the first set from Świątek, who rallied after that to eventually ease past the then-newcomer to the WTA Tour.

Zheng has had a bit more dramatic path to the final. She survived the last two matches in tiebreakers, including ending German Angelique Kerber’s career on Wednesday in the quarterfinals.

This story has been updated with additional information.