Parmentier was in danger of bowing out on day one of the clay-court event, but the seventh seed rallied to win 2-6 6-1 6-4.

The Frenchwoman, a quarter-finalist in Bucharest last year, won six games in a row to take the second set and recovered from losing the first two games of the decider to set up a meeting with Yafan Wang, who eased past Miriam Bulgaru.

Polona Hercog also got herself out of trouble to reach round two, seeing off another Romanian in the form of Elena-Gabriela Ruse 2-6 6-2 6-3.

Arantxa Rus could face top seed Anastasija Sevastova in the second round following a straight-sets defeat of Mariana Duque-Marino, while Tamara Zidansek and Maryna Zanevska also advanced.

Arruabarrena fell at the first hurdle in Gstaad, where 19-year-old Vondrousova toppled the sixth seed.

Veronika Kudermetova and Mona Barthel made it through at the expense of Jil Teichmann and Natalia Vikhlyantseva respectively.