Updated

Oft-injured American Bethanie Mattek-Sands stunned former champion Li Na in Thursday's second-round action at the French Open.

Following a tight first set, it was all Mattek-Sands over the last two as the Minnesota native picked up 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 a wet, chilly day.

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 Australian Open runner-up and captured the lone Grand Slam title of her career at the 2011 French Open.

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 in Paris three years ago.

Meanwhile, 17th-seeded Sloane Stephens improved to 7-1 in Grand Slam action this year with a workmanlike 6-1, 6-3 spanking of fellow American Vania King, and 18th-seeded former world No. 1 Jelena Jankovic of Serbia drubbed Spaniard Garbine Muguruza 6-3, 6-0 to reach the round of 32.

Rain, as it has a few times already this week, interrupted play for several hours on Day 5.

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, Chinese Zheng Jie leveled American Melanie Oudin 6-3, 6-1.