Defending champion and world No.1 Iga Swiatek has been knocked out of the US Open in a 3-6 6-3 6-1 loss to her Latvian nemesis Jelena Ostapenko.
To add insult to injury, the defeat also means Swiatek's reign at the top of the WTA rankings will end next week, when she will be replaced by current No.2 Aryna Sabalenka.
Ostapenko's win was not necessarily a huge surprise, based on the pair's previous match-ups: the 2017 French Open winner has now improved to 4-0 against Swiatek over their careers.
No other player owns four victories against the woman who had led the WTA rankings since April 2022.
Swiatek said there were "some sad emotions" about falling from No.1, although she also described her reign as "pretty exhausting".
Not long after being assured of losing her grip on that perch, the 22-year-old from Poland already was thinking ahead to returning there.
"For sure when I'm going to be, next time, in the same situation, I'm going to do some stuff differently," Swiatek said, "because it was a little bit stressful, and it shouldn't be."
She also sounded mystified about what happened on Sunday.
"I'm just surprised that my level changed so drastically, because usually when I play bad, I play bad at the beginning, then I kind of catch up or just problem-solve. This time it was totally the opposite," Swiatek said.
"I don't really know what happened with my game. I felt no control suddenly."
The 20th-seeded Ostapenko offered a theory.
"The main thing is that she doesn't really like to play against big hitters. She likes to have some time," said Ostapenko, who accumulated 31 winners to 18 for Swiatek.
"When I play fast, aggressive and powerful, she's a little bit in trouble."
Ostapenko, 26, will next face sixth-seeded teenager Coco Gauff, who ended Caroline Wozniacki's US Open comeback with a 6-3 3-6 6-1 victory.
Wozniacki, who returned to Flushing Meadows for the first time since 2019 after coming out of retirement following the birth of her two children, kept Gauff on her toes for two sets but the Dane's lack of match practice caught up with her.
Gauff handed Wozniacki a break with an unforced error in the first game of the match but levelled the contest in the fourth game and broke the 2018 Australian Open champion to love in the eighth.
The young American lost her edge completely in the second set, where the mistakes piled up and she was forced to defend five break points across her first three service games.
Gauff handed her opponent another break in the opening game of the third set but broke back immediately and ran away with the set.
"She's back and it's like she never left," Gauff said of her opponent, who has twice made the final at the US Open.
"To be out here on the court with her today was an honour."
Tenth seed Karolina Muchova reached the quarter-finals with a 6-3 5-7 6-1 victory over China's Wang Xinyu and will play 30th seed Sorana Cirstea, who beat the 15th seed Belinda Bencic 6-3 6-3.
- with AP