Eighth seed Petra Kvitova came back from a set down to beat Veronica Cepede Royg 3-6 6-1 7-5 and reach the French Open second round.
The Czech, among the title favourites, made a shaky start with 17 unforced errors in the first set.
The two-time Wimbledon champion improved in the second but took until the 11th game of the third set for the decisive break against the Paraguayan, reports BBC.
Ex-world number one Victoria Azarenka lost 7-5 7-5 to Katerina Siniakova.