Second-seeded Yanina Wickmayer and third seed Ksenia Pervak led the charge into the quarterfinals at the Gastein Ladies clay-court tennis event.
The Belgian Wickmayer handled last year's Bad Gastein runner-up Patricia Mayr- Achleitner 7-6 (7-4), 6-3, while the Russian Pervak pasted German Sarah Gronert 6-2, 6-3 in second-round action at Hotel Europaischerhof. The Austrian Mayr-Achleitner lost to Spaniard Maria Jose Martinez Sanchez in last year's title match.
Wickmayer will face another Austrian, Yvonne Meusburger, on Friday, while Pervak will take on little-known 19-year-old American qualifier Chichi Scholl, who upset sixth-seeded Romanian Irina-Camelia Begu 6-3, 6-4 on Day 4.
Another upset came when Luxembourg's Mandy Minella took out fourth-seeded Carla Suarez Navarro of Spain 6-2, 3-6, 6-3.
In other play involving seeds, No. 7 Alize Cornet of France leveled New Zealand's Sacha Jones 6-3, 6-2 and No. 8 Swede Johanna Larsson whipped 37- year-old American Jill Craybas 6-2, 6-3.
Additionally, Spaniard Estrella Cabeza Candela downed Dutch qualifier Richel Hogenkamp 6-4, 6-3 and the 2007 Bad Gastein runner-up Meusburger bested Bulgarian qualifier Dia Evtimova 6-2, 6-3.
Friday's other quarterfinals will pit Cornet against Cabeza Candela and Larsson versus Minella.
The 2012 Bad Gastein champion will claim $37,000.