Dutch qualifier Richel Hogenkamp upset top-seeded and 2010 champion Julia Goerges 3-6, 6-3, 6-3 at the Gastein Ladies in a first-round match that was interrupted for four hours because of rain on Tuesday.
The German won the opening set against the 211th-ranked Hogenkamp, who made her debut on the WTA tour, before play was suspended.
It was Goerges' second straight defeat against a Dutch opponent after losing to Arantxa Rus in the third round of the French Open.
Three other seeds advanced as No. 2 Yanina Wickmayer of Belgium defeated Mariana Duque-Marino of Colombia 6-3, 6-4; No. 4 Carla Suarez Navarro of Spain won against Marta Domachowska of Poland 6-4, 7-5; and No. 7 Alize Cornet of France beat Edina Gallovits-Hall of Romania 7-5, 7-5.
Mandy Minella of Luxembourg, Sarah Gronert of Germany and Sacha Jones of Australia also reached the second round.