Top-seeded Petra Kvitova of the Czech Republic eased past Rebecca Marino of Canada 6-2, 6-2 on Tuesday to advance to the second round of the Generali Ladies.
The Wimbledon champion, ranked a career-high fourth, had four aces and broke Marino twice in each set.
Third-seeded Jelena Jankovic of Serbia led 4-1 in the first set when Kateryna Bondarenko pulled out with a neck injury. The Ukrainian player broke Jankovic once but did not score a point in her three service games.
In the second round, Jankovic will play Britain's Anne Keothavong, who defeated Ekaterina Makarova of Russia 6-4, 6-1.
Earlier, Julia Goerges saved two match points in a third-set tiebreaker before beating Anastasija Sevastova 6-4, 3-6, 7-6 (7).
The sixth-seeded German player held serve on the first match point before her Latvian opponent double-faulted on the second chance. Goerges then converted her first match point to set up a second-round match against Evgeniya Rodina of Russia.
The fourth-seeded Anastasia Pavlyuchenkova of Russia defeated Anabel Medina Garrigues of Spain 6-4, 2-6, 6-3. Pavlyuchenkova went 5-0 up in the decider and missed three match points before eventually closing out the win against Medina Garrigues.
Seventh-ranked Dominika Cibulkova of Slovakia saved two match points in the second set before Elena Baltacha of Britain pulled out with a lower back injury early in the third set while trailing 4-6, 7-6 (3), 1-0.
Also advancing from the first round were Sara Errani of Italy, Ksenia Pervak of Russia, Sorana Cirstea of Romania, and Lucie Safarova of the Czech Republic.