Aryna Sabalenka and Jessica Pegula, the top two seeds, were bounced from the Wuhan Open in the second round on Wednesday in China.

Unseeded American Ann Li stunned No. 1 seed Sabalenka, of Belarus, to capture a gripping 3-6, 6-4, 7-6 (5) victory -- the biggest win of her career by ranking, against the world's No. 2 player.

Jelena Ostapenko of Latvia also came from behind to oust No. 2 Jessica Pegula 2-6, 7-6 (7), 6-3.

Li fell behind by a set and a break, with Sabalenka serving up 4-3 only to lose serve on the second break point. Li went on to win the following two games, then jumped to a 5-2 lead in the third set.

A three-time winner in Wuhan, Sabalenka forged back. She fought off five match points to move the score to 5-3, then broke Li to get back on serve after quashing two more match points, eventually sending the match to a tiebreak.

Up 6-3, Li had three more match points, finally winning on her 10th match point.

"It was a crazy match," Li said in her on-court interview after the two-hour, 27-minute thriller. "I didn't start out as well as I would like.

"I had a lot of match points. I missed some opportunities, but she also played well in some of those. I just tried to play each point and stay aggressive."

This is Sabalenka's second consecutive second-round loss to an opponent ranked below 25th. She lost to Czech Nikola Bartunkova earlier this month in straight sets at the China Open in Beijing.

Pegula needed just 31 minutes to win the first set against Ostapenko, cashing in on both break chances while not facing any.

In the second set, the players traded a pair of breaks apiece to roll into a tiebreak. Pegula squandered three match points and then dropped the next two points on her serve to give Ostapenko a set point, which she converted.

In the third set, Ostapenko used four aces, three breaks and a 15-3 lead in winners for the victory. Overall, she hit 45 winners in the match, 30 more than Pegula.

"It's a great atmosphere. I have so many fans here," Ostapenko said after the two-hour, 23-minute match. "Jess is a great player. She has also lot of fans. It's always tough matches against her. I honestly don't know how I managed to win the second set.

"I had a lot of pain in my arm. I took a painkiller and I was fighting for every single point. ... I'm so happy to be through."

In the third round, Ostapenko will face Canada's Leylah Fernandez, who defeated Han Shi of China 6-3, 6-4. Li will meet Janice Tjen of Indonesia, a 7-5, 6-3 winner over Daria Snigur of Ukraine.

The third round also will include matches between: No. 5 Elina Svitolina of Ukraine and China's Hanyu Guo; No. 6 Karolina Muchova of the Czech Republic and No. 11 Diana Shnaider of Russia; No. 7 seed Iga Swiatek of Poland and Ashlyn Krueger; No. 10 Iva Jovic and No. 16 Maja Chwalinska of Poland; and No. 15 Jasmine Paolini of Italy, set to play Sonay Kartal of Great Britain.