Poland's Agnieszka Radwanska and last year's runner-up Li Na of China were among several easy winners, while Denmark's Caroline Wozniacki fell victim to Tuesday's lone upset at the Sydney International, a final Australian Open tune-up.
Last week's Auckland champion and the 2012 Wimbledon runner-up Radwanska, who is the top seed at this event, popped four aces and converted on 6-of-10 break chances en route to a 6-4, 6-3 victory over 42-year-old Japanese qualifier Kimiko Date-Krumm.
The fourth-seeded Li, the 2011 Sydney champ and last week's titlist in Shenzhen, China, dropped just one game during a dominant 6-1, 6-0 decision over Japanese qualifier Ayumi Morita to advance to the quarterfinals. Morita capitalized on her only break opportunity, but also had a pair of double faults and allowed Li to break her serve six times.
Li lost to reigning world No. 1 Victoria Azarenka in last year's Sydney finale.
The seventh-seeded former world No. 1 Wozniacki dropped a 7-6 (7-4), 1-6, 6-2 decision to fellow former top-five star Svetlana Kuznetsova in a nearly three-hour match, as the Russian veteran ripped off seven aces and was aided by five double faults by Wozniacki.
No. 3 seed Sara Errani of Italy cruised to an easy win with a 6-1, 6-1 decision over Russia's Maria Kirilenko, while Germany's No. 2 seed Angelique Kerber had a little more resistance during a 6-2, 7-5 win over Kazakhstani qualifier Galina Voskoboeva.
American qualifier Madison Keys followed her stunning victory over Czech veteran Lucie Safarova in the opening round with a 6-0, 6-4 win over China's Jie Zheng.
Tuesday's other second-round matches saw Slovakia's Dominika Cibulkova advance to the quarters with a 7-6 (7-3), 1-6, 7-6 (7-1) decision over Ekaterina Makarova of Russia and Italy's Roberta Vinci rally to top Serbia's former No. 1 star Jelena Jankovic, 3-6, 6-4, 7-6 (7-4). Jankovic reached the Sydney final back in 2007.
Wednesday's quarterfinals will pit Radwanska against Vinci; Kerber versus the qualifier and 2008 Sydney runner-up Kuznetsova; the French Open runner-up Errani against Cibulkova; and Li versus Keys.