Stosur downed Alize Cornet 7-6 (8-6), 7-5 and will go against Klara Zalopalova in Friday's quarters. Ivanovic defeated Russian Valaria Solovieva 6-1, 6-4 and will meet fellow Serb Vesna Dolonc in the quarters. Dolonc advanced by downing Simona Halep, 6-1, 6-0.
"I played a good match and I'm very glad I advanced to the quarterfinals," Ivanovic said after her second round match. "Earlier into the match my opponent was obviously too nervous as it was the first time she played at such a high level. But she started to play better in the second and was making fewer errors."
Also advancing was No. 7 seed Maria Kirilenko, who defeated Yaroslava Shvedova of Kazakhstan, 7-5, 6-4.
In other quarterfinals, Kirilenko takes on Sofia Arvidsson and No. 3 Carolina Wozniacki plays fifth seed Dominika Cibulkova.