Paris, France (SportsNetwork.com) - Serena Williams and Petra Kvitova were both tested before advancing, while former world No. 1 Caroline Wozniacki was a second-round upset victim Thursday at the 2015 French Open.
The world No. 1 Williams improved to 27-1 this year by coming from behind to beat game German Anna-Lena Friedsam 5-7, 6-3, 6-3 on Court Lenglen.
Williams, who is now 7-0 in three-set matches this season, is a 19-time Grand Slam champion who owns two French Open titles (2002, 2013). She currently holds the Australian and U.S. Open crowns and has won her last 16 matches at the majors.
Up next for the powerful American will be 27th-seeded former No. 1 Victoria Azarenka, who cruised past Czech Lucie Hradecka 6-2, 6-3. Azarenka is a two- time Aussie Open champ and two-time U.S. open runner-up to Williams.
Williams is 15-3 lifetime against Azarenka, including 8-0 in Grand Slam competition.
The Belarusian Azarenka reached the French semis in her last trip to Paris in 2013.
Kvitova, meanwhile, hasn't had much success on the famed red clay at Roland Garros, with five losses prior to the quarterfinals in six previous appearances. She needed three sets to win her first-round match on Tuesday and again went the distance on Day 5.
The two-time Wimbledon champ misfired for 45 unforced errors, but survived with a 6-7 (4-7), 6-4, 6-2 victory over Spain's Silvia Soler-Espinoza to advance to the third round. Despite her troubles in the French capital, the fourth-seeded Kvitova did enter this year's second major with some solid results on the slow surface, winning the Madrid Open before a quarterfinal appearance in Rome.
Next up for Kvitova will be 30th-seeded Romanian Irina-Camelia Begu, who rolled to a 6-2, 6-0 victory over Croatia's Ana Konjuh.
The 2014 U.S. Open runner-up Wozniacki has struggled even more than Kvitova in Paris and again made an early exit with a 6-4, 7-6 (7-4) loss against Germany's Julia Goerges.
The fifth-seeded Dane has been past the third round only once in nine visits to Roland Garros -- a quarterfinal result in 2010. She was a first-round loser last year and departed in the second round in 2013.
With Wozniacki's exit, the women's draw has now lost three of the top-six seeds, including No. 3 Simona Halep and No. 6 Genie Bouchard.
Goerges, who has never advanced beyond the fourth round in any of her previous 28 Grand Slam events, will play American Irina Falconi in the third round. Falconi advanced with a 3-6, 6-1, 6-2 triumph over Bulgaria's Sesil Karatantcheva.
Tenth-seeded German Andrea Petkovic rallied for a 4-6, 6-4, 6-4 win over Spain's Lourdes Dominguez Lino and will next play 17th-seeded former French Open runner-up Sara Errani, who also needed three sets to dispose of Germany's Carina Witthoeft, 6-3, 4-6, 6-2.
Also on Thursday, Romanian Andreea Mitu surprised 12th-seeded Czech Karolina Pliskova 2-6, 7-6 (7-5), 6-4 and in a battle of former French Open champs, Italian Francesca Schiavone outlasted 18th-seeded Russian Svetlana Kuznetsova 6-7 (11-13), 7-5, 10-8 in 3 hours, 50 minutes -- the sixth-longest women's match in the Open Era (since 1968).
The Kuznetsova-Schiavone match still fell a way short of the 4 hours, 44 minutes it took Schiavone to beat Kuznetsova 16-14 in the deciding set at the Australian Open in 2011 -- a Grand Slam record for a women's match.
Kuznetsova served for the match four times from 5-4 in a gripping deciding set on Thursday, but each time the scrappy 34-year-old Schiavone, the oldest player to reach the second round, refused to buckle and broke back.
"You fight, you fight, and then you are reaching the mountain top, then you go down again and you fight and go up. It's tough," said Schiavone. "With Svetlana I think we can play hours and hours and hours because we know each other exactly.
"She is amazing, and every time I play against her I say, Oh, my God, now what can happen?"
Rising 16th-seeded American Madison Keys landed in the round of 32 by besting Swiss fellow young gun Belinda Bencic, 6-0, 6-3, while on-the-move 23rd-seeded Swiss Timea Bacsinszky drilled Czech Tereza Smitkova 6-2, 6-0 and Belgian Alison Van Uytvanck upset 32nd-seeded Zarina Diyas of Kazakhstan's 0-6, 6-1, 6-4. Keys' third-round opponent will be Bacsinszky.
Some other second-round results saw American Sloane Stephens douse Brit Heather Watson 6-2, 6-4, France's Kristina Mladenovic get past Montenegro's Danka Kovinic 6-3, 7-5 and Bulgarian Tsvetana Pironkova take care of Czech Denisa Allertova 6-3, 7-6 (7-2).
American women went a perfect 4-0 in the second round.
The third round will get underway on Friday, including matches for second- seeded defending champion Maria Sharapova and former French Open titlist Ana Ivanovic.
The former world No. 1 Sharapova will take on 26th-seeded former U.S. Open champion and former Roland Garros finalist Samantha Stosur, while the seventh- seeded Ivanovic will face Croat Donna Vekic. Stosur is fresh off her clay- court title last week in Strasbourg here in France.
The five-time Grand Slam champion Sharapova titled here in 2012 and last year and was the runner-up in Paris in 2013. Sharapova beat Simona Halep in last year's Roland Garros finale.
Several other seeded women will take to the courts on Day 6, including No. 8 Spaniard Carla Suarez Navarro, No. 9 Russian Ekaterina Makarova and No. 11 German Angelique Kerber.