Shenzhen, China (SportsNetwork.com) - Top seed and defending champion Li Na eased into the quarterfinals, while second-seeded Sara Errani was among Wednesday's upset victims at the $500,000 Shenzhen Open tennis event, a hardcourt Australian Open tune-up.

The 2013 Aussie Open runner-up Li handled Ukrainian qualifier Nadiya Kichenok 6-1, 6-4, while American Vania King fought back to upend the world No. 7 Italian Errani 2-6, 7-6 (9-7), 6-3 at Shenzhen Longgang Tennis Center.

The world No. 3 former French Open champion Li won last year's inaugural Shenzhen title by beating Czech Klara Zakopalova in the finale. The Chinese tennis hero's quarterfinal opponent on Thursday will be Romanian Monica Niculescu.

More upsets came when Austrian Patricia Mayr-Achleitner ousted a third-seeded Zakopalova 7-6 (7-2), 6-4 and Czech Barbora Zahlavova Strycova took out seventh-seeded Chinese favorite Zheng Jie 6-0, 7-6 (8-6).

Eighth-seeded German Annika Beck avoided an upset by outlasting Swiss qualifier Viktorija Golubic 6-3, 5-7, 6-3.

Two other second-rounders saw Slovak Jana Cepelova drop German qualifier Anna- Lena Friedsam 6-4, 6-1 and Niculescu overcome Taipei's Yung-Jan Chan 2-6, 6-3, 6-0.

The other quarterfinals will pit fifth-seeded Chinese Peng Shuai against Cepelova, Beck versus Mayr-Achleitner, and Zahlavova Strycova against King.