Italy's Roberta Vinci opened her title defense at the St. Petersburg Ladies Open with a 6-3, 3-6, 6-4 victory over Hungary's Timea Babos in the first round of Tuesday.
Babos broke serve against the sixth-seeded Vinci five times, but was unable to upend the reigning champion.
Vinci will face Germany's Andrea Petkovic or Romania's Irina-Camelia Begu in the second round.
France's Kristina Mladenovic tipped Belgium's Elise Mertens 7-6 (5), 6-4 and Kazakhstan's Yulia Putintseva toppled Sweden's Johanna Larsson 6-1, 1-0 after Larsson retired from the match on Tuesday.
Mladenovic will face Australian Open finalist Venus Williams while Putintseva counters Germany's Annika Beck in the next round.