Former world number one Caroline Wozniacki is the third top-six seed to be knocked out of the French Open after slumping to a 6-4, 7-6 (7/4) loss to Germany's Julia Goerges.Fifth seed Wozniacki joins third-seeded Simona Halep as a second-round casualty while sixth seed Eugenie Bouchard was defeated in the first round.
Goerges, who has now matched her best result in Paris, will face Irina Falconi of the United States for a place in the last 16.
Falconi beat Bulgarian Sesil Karatantcheva 3-6, 6-1, 6-2.
Seventeenth seed Svetlana Kuznetsova joined Wozniacki on the losers' list after she went down to Francesca Schiavone.
The match was an absolute marathon, with 2010 French Open champion Schiavone finally winning 6-7 (11/13), 7-5, 10-8.
Fourth seed Petra Kvitova reached the third round with a 6-7 (4/7), 6-4, 6-2 win over Spaniard Silvia Soler-Espinosa.
The Wimbledon champion will play either Ana Konjuh of Croatia or Irina-Camelia Begu of Romania for a place in the last 16.
Tenth seed Andrea Petkovic was forced to come back from a set down but eventually overcame Lourdes Dominguez Lino 4-6, 6-4, 6-4 to advance.
On the men's side, Japanese fifth seed Kei Nishikori reached the fourth round when scheduled last-32 opponent Benjamin Becker withdrew with a shoulder injury.
"Benjamin Becker withdraws with right shoulder injury, Nishikori advances to R16. Wishing Benjamin a speedy recovery," tweeted the official Roland Garros website.
Nishikori will face either Lukas Rosol of the Czech Republic or Teymuraz Gabashvili of Russia for a place in the quarter-finals.
"Very sorry to hear about Benjamin being injured. I hope he recovers fast," tweeted Nishikori, who also made the fourth round in 2013.
Becker, 33, needed two gruelling five-setters to get to the third round, seeing off Ruben Bemelmans of Belgium and Spanish 32nd seed Fernando Verdasco.
The man who beat Nishikori in last year's US Open final, ninth seed Marin Cilic, reached the third round in Paris on Wednesday night (AEST) with a straight-sets win over Andrea Arnaboldi.
The Italian put up a fight in the first set, but ultimately could not stay with the US Open champion, losing 7-6 (7/3), 6-1, 6-1.
There was something of an upset later in the day when German 22nd seed Philipp Kohlschreiber fell to world number 42 Pablo Andujar.
Kohlschreiber finished the match leading the ace count 12-1 and the winners count 66-52, but failed to land his first serve regularly enough.
He dropped the first two sets but looked to be staging a comeback by winning the third and fourth, only to eventually leave the tournament after a brutal 6-1, 7-6 (7/5), 3-6, 3-6, 6-4 loss.