BEIJING -- After a three-week break, US Open semifinalist Coco Gauff beat Camila Osorio 7-6 (4), 4-6, 6-2 in a second-round match at the China Open on Saturday.
No. 1-ranked Elena Rybakina was later ousted by No. 118 Alina Charaeva of Armenia. Charaeva held her head in her hands in disbelief after winning 3-6, 6-4, 6-3.
"I was just trying to stay really hard mentally and keep believing that at some point I could turn it around again to my side. And I guess I just never stopped believing," said Charaeva, only the ninth woman outside the top 100 to beat a No. 1 player.
Rybakina had seven double faults and dropped her serve five times, the last time to fall behind 4-2 in the third set.
The new US Open champion, Rybakina became only the second woman to lose her first match as world No. 1. Naomi Osaka was the other, in 2019.
"There was a lot going on after the US Open victory. I didn't get a lot of chances to sleep and recover," Rybakina said. "Congratulations to Alina. She played a very good match."
Gauff won her first match since losing to Rybakina in three sets in the final four at Flushing Meadows on Sept. 11. She is a two-time singles major champion, having won the 2023 US Open and 2025 French Open, defeating Aryna Sabalenka in both finals.
The WTA 1000-level, 128-draw tournament ends Oct. 11 in Beijing.
In the corresponding men's ATP 500 tournament, top seed and US Open champion Alexander Zverev beat wild-card entry Shang Juncheng 6-0, 6-3 to set up a quarterfinal against Novak Djokovic.
Third-seeded Daniil Medvedev advanced by beating Jan-Lennard Struff 6-4, 6-3, and Alex de Minaur defeated Quentin Halys 3-6, 7-6 (5), 7-5.