Chinese ace Zheng Jie worked hard to take a 6-3, 2-6, 6-3 win over former world number one Maria Sharapova Sunday to reach the fourth round of the BNP Paribas Open in Indian Wells.

Zheng's compatriot Peng Shuai, however, lost to Russian 16th seed Nadia Petrova 1-6, 5-7 in a later match.

Australian Open semifinalist Zheng next faces Alicia Molik, who cruised into the round of 16 with a 6-0, 6-2 victory over British qualifier Elena Baltacha.

Zheng toiled for two hours, 43 minutes to dispatch the 10th-seeded Sharapova - the second set alone taking 68 minutes.

With the victory, Zheng improved on her previous best Indian Wells performance - a third-round appearance in 2008.

Sharapova won the title in the California desert in 2006, but didn't play singles here last year as she continued her recovery from shoulder surgery.

In other women's matches, fourth-seeded Russian Elena Dementieva downed Belgian Kirsten Flipkens 6-4, 6-2, setting up a clash with France's Aravane Rezai, who outlasted Italy's Francesca Schiavone 6-7 (4-7), 7-6 (7-2), 6-4.

Fifth-seeded Agnieszka Radwanska of Poland beat Argentina's Gisela Dulko 6-1, 6-0, advancing to a fouth-round meeting with France's Marion Bartoli - a 6-2, 6-0 winner over American Jill Craybas.