Peyton Stearns highlighted a day of upsets by recording a 6-3, 1-6, 6-2 win over 17th-seeded Jelena Ostapenko on Wednesday at the French Open in Paris.
Russians Anna Blinkova and Anastasia Pavlyuchenkova, and Kazakhstan's Yulia Putintseva also knocked off seeded foes to advance at Roland Garros.
Stearns, a former player at the University of Texas, benefited from 28 unforced errors to lower the boom on Ostapenko, a 2017 French Open champion.
"It was definitely crazy, nerve-wracking, overwhelming -- all of the emotions into one," the 21-year-old Stearns said. "But I think at the end I settled down and was really able to come to peace with myself and play my tennis instead of who I was playing, where I was playing and whatnot.
"It's not super surprising to me. If I go out there and play my game then the best can come. Trying to play not to lose but to win is a big thing. And that's what happened today."
Stearns advanced to set up a match against No. 9 seed Daria Kasatkina, a 6-3, 6-4 winner over Marketa Vondrousova of the Czech Republic. Kasatkina advanced to the semifinals at last year's French Open.
"It's fun to watch, but to play against Marketa is very tough," Kasatkina said. "Physically it was a big battle. The second set was so tough."
Blinkova rallied from a set down to post a 4-6, 6-3, 7-5 win over fifth-seeded Caroline Garcia of France. Blinkova also defeated Garcia in the second round of the 2019 French Open.
Pavlyuchenkova also overcame a first-set setback to notch a 4-6, 7-5, 7-5 victory over 15th-seeded Liudmila Samsonova of Russia.
Putintseva bounced 19th-seeded Qinwen Zheng of China with a 6-3, 4-6, 6-2 decision.
Also on Wednesday, second-seeded Aryna Sabalenka collected a 7-5, 6-2 win over Belarus countrywoman Iryna Shymanovich, while third-seeded Jessica Pegula posted a 6-2 win in the first set against Italian Camila Giorgi before the latter retired due to injury.
No. 24 Anastasia Potapova overcame dropping the first set to seize a 3-6, 6-4, 6-1 win over Mayar Sherif of Egypt. No. 27 Irina-Camelia Begu of Romania bested Sara Errani 6-3, 6-0. No. 28 Elise Mertens of Belgium topped Camila Osorio of Colombia 6-3, 7-6 (3).
Also, Sloane Stephens defeated Varvara Gracheva in straight sets.
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