Caroline Wozniacki's surprise exit in the French Open second round capped another tough day for the seeds at Roland Garros.

After Eugenie Bouchard and Simona Halep were beaten in the two previous days, Wozniacki became the third top 10 seed to bow out as Julia Goerges secured a 6-4 7-6 (7-4) win.

The Dane was one of four seeded players to suffer defeat on Thursday, although she was by far the highest-profile.

Karolina Pliskova, Zarina Diyas and Svetlana Kuznetsova all joined the world number five as they were beaten by Andreea Mitu, Alison Van Uytvanck and Francesca Schiavone.

Schiavone may well be weary when she faces Mitu in the next round, after seeing off 2009 champion Kuznetsova in a thrilling encounter that lasted three hours 50 minutes as the Italian prevailed 6-7 (11-13) 7-5 10-8.

There were scares all over the draw as Serena Williams, Petra Kvitova and Andrea Petkovic all lost their opening sets, but were able to rectify their respective matches and move into the next round.

Williams' wobble came against world number 105 Anna-Lena Friedsam, but she showed her character to win 5-7 6-3 6-3 and set up a clash with Victoria Azarenka – who beat Lucie Hradecka in straight sets. 

After losing a first set tie-break to Silvia Soler-Espinosa, Kvitova rallied to claim a 6-7 (4-7) 6-4 6-2 success, while Petkovic came from a set down to beat Lourdes Dominguez Lino 4-6 6-4 6-4.

It was a much easier day for 16th seed and last year's semi-finalist Madison Keys as she breezed past Belinda Bencic 6-0 6-3, while fellow American Sloane Stephens was similarly emphatic in beating Heather Watson.

Sara Errani and Timea Bacsinszky completed the seeds booking their third-round spots, while there were also triumphs for Irina Falconi, Irina Begu, Tsvetana Pironkova and Kristina Mladenovic.