Ivanovic, a finalist at the 2008 Australian Open and the winner at the French Open, was routed, 6-1, 6-4. Ivanovic barely survived a tough match in the second round but was dominated by the 133rd-ranked Zheng.
The fourth round will pair two Americans against each other as Bethanie Mattek upset 11th-seeded Marion Bartoli, 6-4, 6-1. That gave her a shot at sixth-seeded Serena Williams, who was a 7-6 (7-5), 6-1 winner Friday over No. 29-seeded Amelie Mauresmo. Both Bartoli and Mauresmo were hampered in the second sets by injury.
No. 4-seeded Svetlana Kuznetsova and eighth-seeded Anna Chakvetadze were straight-set, third-round winners. Kuznetsova breezed past Barbora Zahlavova Strycova, 6-2, 6-4, and Chakvetadze was 6-4, 6-3 winner over Evgeniya Rodina.
The fourth-round pairings have Kuznetsova going against Radwanska and Chakvetadze playing Vaidisova.