World number one Naomi Osaka avoided a premature end to her bid for a third straight Grand Slam title by coming from behind to reach the French Open second round.
She twice had to stop Slovakia’s Anna Karolina Schmiedlova serving out the match before winning 0-6 7-6 (7-4) 6-1.
The Japanese, 21, faces two-time Grand Slam champion Victoria Azarenka next.
Defending champion Simona Halep struggled in a 6-2 3-6 6-1 win over world number 47 Ajla Tomljanovic.
Schmiedlova, ranked 90th in the world, made very few errors until victory was in sight, but the pressure of a career-best win told as Osaka fought back.
US Open and Australian Open champion Osaka is playing in her first Grand Slam as the top seed.
Both Osaka and Halep were playing on Philippe Chatrier, the main court at Roland Garros, and both wobbled against low-ranked opponents.
Romanian Halep, whose only Grand Slam triumph came in Paris last year, looked as though she would breeze through the match at first, winning the first set in less than half an hour.
But Tomljanovic broke Halep’s serve twice to take the second set, before the world number three closed out the match in dominant fashion after four breaks in the third.
Halep, 27, is hoping to become the first player to defend the women’s singles title since Belgian Justine Henin achieved the feat in 2007.
She faces Polish world number 87 Magda Linette in the second round.
American 14th seed Madison Keys enjoyed a much more straightforward win, beating Russia’s Evgeniya Rodina 6-1 6-2, while Belarusian 11th seed Aryna Sabalenka defeated former Grand Slam finalist Dominika Cibulkova 7-5 6-1.
In one of the most anticipated ties of the round, Azarenka, 29, beat 2017 French Open champion Jelena Ostapenko 6-4 7-6 (7-4).
