Sydney, Australia (Sports Network) - Poland's Agnieszka Radwanska and China's Li Na were among several easy winners, while Denmark's Caroline Wozniacki fell victim to Tuesday's lone upset at the Sydney International.
Radwanska, who is the top seed at this event, reeled off four aces and converted on 6-of-10 break chances en route to a 6-4, 6-3 victory over Kimiko Date-Krumm of Japan.
Li, the 2011 Sydney champ, 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 the fourth-seeded Li to break her serve six times.
Wozniacki, however, dropped a hard-fought 7-6 (7-4), 1-6, 6-2 decision to Svetlana Kuznetsova in a nearly three-hour match, as the Russian 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 Kazakhstan's 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 Jelena Jankovic, 3-6, 6-4, 7-6 (7-4).