Former world No. 1 Victoria Azarenka was an easy second-round winner, while American Bethanie Mattek-Sands stunned former champion Li Na in Thursday's action at the French Open.
The third-seeded Azarenka handled young German Annika Beck 6-4, 6-3 on Court Lenglen. The shrieking Belarusian star is the reigning Australian Open champion and was last year's U.S. Open runner-up.
Meanwhile, the oft-injured Minnesota native Mattek-Sands recorded the biggest win of her career by dousing the sixth-seeded Li in 5-7, 6-3, 6-2 fashion in 2 hours, 16 minutes on Court 1 at Stade Roland Garros.
The 67th-ranked Mattek-Sands won seven straight games at one point to grab a commanding 5-0 lead in the final set on another wet, chilly day in Paris.
Li refused to make any excuses after the loss.
"I know for sure that I don't normally lose seven games in a row," she said. "It was very tough conditions, coming back to the court three times. But for both players it was the same.
"I should find out what happened and I'll talk to myself, my team to see what happened."
The 28-year-old Mattek-Sands posted the fourth top-10 win of her career and her second of 2013. She upset 2012 French Open runner-up Sara Errani on red clay in Stuttgart last month.
Li was this year's Aussie Open runner-up to Azarenka and captured the lone Grand Slam title of her career at the 2011 French Open.
Seventh-seeded former Wimbledon champion Petra Kvitova improved to 7-1 in her last two trips to the French with a 6-4, 6-3 victory over last week's Brussels runner-up Peng Shuai of China, while ninth-seeded former Roland Garros finalist Sam Stosur reached the third round with a 6-4, 6-3 handling of France's Kristina Mladenovic. The former U.S. Open champion Stosur was the runner-up here three years ago.
Sloane Stephens, seeded 17th at this fortnight, improved to 7-1 in Grand Slam action this year with a workmanlike 6-1, 6-3 spanking of fellow American Vania King, while 18th-seeded former world No. 1 Jelena Jankovic of Serbia drubbed Spaniard Garbine Muguruza 6-3, 6-0 to reach the round of 32.
In other action involving seeds, New Zealand's Marina Erakovic upended No. 16 Dominika Cibulkova of the Slovak Republic 6-2, 2-6, 6-4 and Argentine Paula Ormaechea took out No. 27 Yaroslava Shvedova of Kazakhstan 6-4, 7-6 (8-6). Ormaechea will face Mattek-Sands in an unlikely third-rounder on Saturday.
Also, American Jamie Hampton beat Slovak Anna Schmiedlova 7-5, 6-2 and Chinese Zheng Jie leveled American Melanie Oudin 6-3, 6-1.
Rain, as it has a few times already this week, interrupted play for several hours on Day 5.