Ana Ivanovic overcame a left thigh injury to beat Pauline Parmentier of France 6-3, 6-2, while Italy's Camila Giorgi routed fourth-seeded Andrea Petkovic 6-1, 6-2 in the opening round of the Generali Ladies on Tuesday.
Ivanovic, who won the event in 2008 and 2010 and reached the final last year, lost her opening service game. But the second-seeded Serb went on to dominate the match until asking for medical treatment while trailing 2-1 in the second set.
The eighth-ranked Ivanovic, who is chasing her fifth title of the season, didn't concede a game afterward to set up a second-round match against Madison Brengle. The American qualifier was leading 7-5, 3-1 when her Romanian opponent Irina-Camelia Begu retired.
The 42nd-ranked Giorgi had four aces and saved all four break points for Petkovic to clinch her third win of the season against the German, who is ranked 16th.
Giorgi next plays Ons Jabeur of Tunisia, who beat Donna Vekic of Croatia 7-5, 6-1.
Also, seventh-seeded Karolina Pliskova of Czech Republic defeated Kirsten Flipkens of Belgium 6-2, 6-4, while Mona Barthel of Germany eased past Kiki Bertens of the Netherlands 6-3, 6-1. Bertens lost in qualifying but replaced Carla Suarez Navarro in the main draw after the Spaniard pulled out with a right elbow injury.
Bulgaria's Tsvetana Pironkova, who won her maiden WTA title in Sydney earlier this year, defeated Austrian wildcard entry Lisa-Marie Moser 6-2, 6-3, and Magdalena Rybarikova of Slovakia beat Kaia Kanepi of Estonia 6-4, 5-7, 6-2.