Roberta Vinci started the defense of her St. Petersburg Ladies' Trophy title with a 6-3, 3-6, 6-4 win over Timea Babos on Tuesday.
The sixth-seeded Italian was broken five times but still advanced to face either German veteran Andrea Petkovic or Irina-Camelia Begu of Romania in the second round.
Also Tuesday, Kristina Mladenovic of France beat Belgian qualifier Elise Mertens 7-6 (5), 6-4 and will next face Australian Open finalist Venus Williams.
Yulia Putintseva of Kazakhstan also advanced, leading 6-1, 1-0 when Swedish opponent Johanna Larsson retired from the match. Putintseva will next face Annika Beck of Germany.