Former world No. 1 Maria Sharapova and reigning Wimbledon champion Petra Kvitova secured quarterfinal berths, while defending French Open champ Li Na was stunned by a qualifier Monday at Roland Garros.
After cruising through her first three matches, the second-seeded Sharapova was tested Monday in a 6-4, 6-7 (5-7), 6-2 victory over unseeded game Czech veteran Klara Zakopalova on Court Chatrier. Sharapova converted on her first match point when the 30-year-old Zakopalova double-faulted to end a 3-hour, 11-minute match that featured no less than 21 service breaks.
"It was a good test for me," Sharapova said. "I had chances to finish in two sets and didn't but I came out strong in the third set. I guess that's really what matters and it's nice to be in the quarters again."
Sharapova advanced despite piling up 12 double faults on a windy, rainy afternoon and had her serve broken three times while serving for the match on Day 9. Her power was diffused on the red clay amid the heavy playing conditions, but she still had enough game to stave off the Zakopalova challenge and improve to 19-1 in three-set matches over the last two seasons.
Zakopalova had never advanced the second round in Paris prior to this particular French fortnight.
The 25-year-old three-time major champion Sharapova, who's now 33-5 this year, still needs a French Open title to complete a career Grand Slam. She reached semifinals here last year and in 2007.
The reigning Australian Open and Wimbledon runner-up Sharapova will meet Estonian slugger Kaia Kanepi in the quarterfinals.
Meanwhile, a fourth-seeded Kvitova, who had her match moved from Chatrier to Court 1, leveled helpless American Varvara Lepchenko 6-2, 6-1 in exactly one hour to reach her first-ever French Open quarter.
Kvitova, who reached the Aussie Open semis back in January, will encounter Kazakhstan's Yaroslava Shvedova in the round of eight.
Shvedova was beaten easily in the first set Monday before roaring back to win 12-of-14 games in a 3-6, 6-2, 6-0 stunner against the seventh-seeded 30-year- old Li on Court Lenglen.
"I will find the 'why,'" Li said when asked what happened Monday. "But not today. Otherwise, for sure, I win the match."
Last year, China's Li reached the Aussie Open final and then captured the French Open title to become the first-ever Asian player to win a Grand Slam tennis championship.
The 142nd-ranked 24-year-old doubles specialist Shvedova will now appear her second Roland Garros quarterfinal in three years. This is the only major tournament where she has reached the round of eight.
Shvedova captured women's doubles titles at Wimbledon and the U.S. Open in 2010.
A 23rd-seeded Kanepi got past lanky Dutchwoman Arantxa Rus 6-1, 4-6, 6-0 to reach her second French Open quarterfinal in five years.
The hard-hitting Kanepi, who will turn 27 on Sunday, doused ninth-seeded former world No. 1 Caroline Wozniacki in the third round this past weekend.
The quarterfinals will commence Tuesday, when sixth-seeded 2010 French Open runner-up and reigning U.S. Open champion Sam Stosur meets 15th-seeded diminutive Slovak Dominika Cibulkova and 10th-seeded German lefthander Angelique Kerber takes on 21st-seeded Italian Sara Errani. Cibulkova stunned world No. 1 Victoria Azarenka in her last outing.