German fifth seed and reigning Wimbledon champion Angelique Kerber was knocked out of Roland Garros in the first round on Sunday by Russian world number 81 Anastasia Potapova.
Kerber, bidding to complete a career Grand Slam, slumped to a 6-4, 6-2 defeat to the 18-year-old who was making her Paris debut.
Kerber had come into Roland Garros carrying a right ankle injury which forced her to pull out of the Italian Open and retire from her second round tie in Madrid.
"I had a lot of confidence and I have to thank my coach for that," said Potapova who hit 28 winners past her German opponent who has now lost six times in the French Open first round.
The Russian's first win over a top 10 player gives her a second round clash against either China's Wang Yafan or Marketa Vondrousova of the Czech Republic.