Wozniacki ran past 16th-seeded Anastasia Pavlyuchenkova 6-1, 6-2 with five service breaks in seven receiving games. Wozniacki fought off four of the five break-point situations she faced.
Zvonareva heads into the quarterfinals after a 6-4, 6-0 win over Roberta Vinci. Zvonareva won 62 percent of the points in the second set.
Kaia Kanepi improved to 3-1 lifetime against Jelena Jankovic, ousting the No. 3-seed 6-4, 6-4 Wednesday. Jankovic lost half her service games.
No. 5-seeded Francesca Schiavone got past Kimiko Date Krumm, who turned 40 Tuesday, 6-3, 6-3 with five service breaks.
Also, sixth-seeded Agnieszka Radwanska topped Andrea Petkovic 6-3, 6-3 and No. 7-seeded Elena Dementieva advanced with a 6-4, 6-2 victory over Flavia Pennetta. Eighth-seeded Victoria Azarenka moved to the quarterfinals when 11th-seeded Marion Bartoli became ill and couldn't continue after the first set, which Azarenka won 6-2.
Qualifier Coco Vandeweghe continued her run with a 6-3, 6-0 triumph over Julia Goerges. Vandeweghe won all but 11 points in the second set.
Thursday's quarterfinals have Wozniacki going against Radwanska and Vandeweghe meeting Azarenka in the top half of the draw while Schiavone plays Kanepi and Dementieva takes on Zvonareva in the lower half.