Second seed Karolina Pliskova was knocked out of Roland Garros by 2017 champion Jelena Ostapenko in the second round on Thursday.
World number 43 Ostapenko triumphed 6-4, 6-2 and will face next either Sloane Stephens, the 2017 US Open winner and runner-up in Paris in 2018, or Spain's Paula Badosa for a spot in the last 16.
Pliskova made the semi-finals in 2017 but has now failed to get beyond the third round in her eight other appearances in the French capital.
"I tried to be aggressive but not miss too much as she's such a great player," said Ostapenko who had lost in the first round in her last two visits to the French Open.
"I had to bring the best tennis that I could."
Latvian Ostapenko, 23, fired 27 winners to Pliskova's nine as the Czech's Grand Slam year ended in further disappointment.
She made the third round at the Australian Open and only second at the US Open but she arrived in Paris having retired from the Italian Open final against Simona Halep with a thigh injury.