MONTREAL -- Maria Sharapova withdrew from the Rogers Cup on Wednesday because of a stomach ailment.
Kvitova, the 2011 Wimbledon champion, quickly finished off Pervak after the match was delayed for 30 minutes by rain with the players tied 4-4 in the second set.
In other second-round matches, fourth-seeded Sam Stosur led Simona Halep 7-5, 4-4 when Halep retired because of left thigh injury; eighth-seeded Sara Errani beat Jana Cepelova 6-3, 6-2, and 16th-seeded Lucie Safarova edged Sesil Karatantcheva 6-4, 6-4.
In first-round play, 18-year-old Canadian Eugenie Bouchard beat Shahar Peer 3-6, 6-2, 7-5. Americans Christina McHale and Varvara Lepchenko also won first-round matches. McHale beat Arantxa Rus 3-6, 6-1, 6-3, and Lepchenko topped Anastasia Pavlyuchenkova 6-2, 6-3.
Information from The Associated Press contributed to this report.