Ninth-seeded Australian Samantha Stosur, who has spoken of her anxiety over playing in front of her home fans, served twice for the match, but double-faulted on match point in a 6-4, 1-6, 7-5 loss to China’s Zheng Jie.
Earlier, fourth-seeded Agnieszka Radwanksa extended the year’s best winning streak to 11 matches. She eased into the third round with a 6-3, 6-3 victory over Romania’s Irina-Camelia Begu and remains unbeaten this year, including titles at warm-up tournaments this month at Auckland and Sydney.
With top-ranked Azarenka and Serena Williams on the other half of the draw, Radwanska’s main obstacles to reaching the final are 2011 French Open champion Li Na, who beat Olga Goortsova of Belarus 6-2, 7-5 to reach the third round, and potential semi-final rivals Sharapova or No. 5 Angelique Kerber, who advanced with a 6-3, 6-1 win over Lucie Hradecka.
In other women’s second-round matches, No. 11 Marion Bartoli beat Serbian qualifier Vesna Dolonc 7-5, 6-0; No. 18 Julia Gorges beat Romina Oprandi 6-3, 6-2; No. 22 Jelena Jankovic, a former world No. 1, beat qualifier Maria Joao Koehler 2-6, 7-6, 6-2; and 17-year-old American wild-card Madison Keys beat No. 30 Tamira Paszek of Austria 6-2, 6-1.
Russian qualifier Valeria Savinykh upset No. 15 Dominika Cibulkova 7-6 (6), 6-4 and Kirsten Flipkens of Belgium beat No. 23 Klara Zakopalova 6-1, 6-0.
On the men’s side, No. 4-ranked David Ferrer needed five match points before clinching a 6-0, 7-5, 4-6, 6-3 win over Tim Smyczek.
Fifth-seeded Tomas Berdych beat Guillaume Rufin of France 6-2, 6-2, 6-4; and eighth-seeded Janko Tipsarevic beat Lukas Lacko 6-3, 6-4, 3-6, 4-6, 7-5 in a match that lasted nearly four hours.
No. 10 Nicolas Almagro and No. 16 Kei Nishikori also moved on, while No. 24 Jerzy Janowicz of Poland rallied from two sets down to overpower India’s Somdev Devvarman 6-7, 3-6, 6-1, 6-0, 7-5.
Also advancing were No. 22 Fernando Verdasco, No. 28 Marcos Baghdatis, No. 31 Radek Stepanek and No. 32 Julien Benneteau. Stepanek beat Feliciano Lopez 6-2, 6-2, 6-4 and will next play Djokovic.
No. 20 Sam Querrey advanced when fellow American Brian Baker retired in the second set with a right-knee injury.