Petra Kvitova saved a match point to reach the French Open second round but Angelique Kerber became the first women's seed to exit the tournament.
Three-time Grand Slam champion Kerber, seeded 26th, was beaten 6-2 6-4 by Ukrainian qualifier Anhelina Kalinina.
Czech Kvitova was in danger of going the same way but recovered to beat Belgium's Greet Minnen 6-7 (7-3) 7-6 (7-5) 6-1.
Meanwhile, Naomi Osaka also advanced but was warned about media boycott.
The Japanese second seed beat Romania's Patricia Maria Tig 6-4 7-6 (7-4) before Grand Slam organizers issued a statement telling her she risked expulsion from the event if she continued to refuse to attend news conferences.
