Zheng took a tight 7-6 (7-4), 2-6, 6-4 victory from Ivanovic in a match that took nearly three hours. The loss dropped Ivanovic to 5-5 since she won the French Open and took over the No. 1 world ranking. Zheng has beaten Ivanovic twice in that span, with one of those wins at Wimbledon.
The rest of the China Open quarterfinals played to form with top-seeded Jelena Jankovic ousting seventh-seeded Daniela Hantuchova, 7-5, 6-1, No. 4-seeded Svetlana Kuznetsova breezing past Dominika Cibulkova, 6-2, 6-4, and fifth-seeded Vera Zvonareva ripping Anabel Medina Garrigues, 6-0, 6-1, in 52 minutes.
Jankovic is paired against Zvonareva in Saturday's semifinals. They have split their six career matches against each other. Kuznetsova and Zheng, who play in the other semifinal, have met once before with Kuznetsova taking a 6-1, 6-0 decision in 2006.
Saturday's semifinals winners meet Sunday with a winner's check of $95,500 at stake.