American Melanie Oudin was knocked out, too, falling 6-3, 6-2 to Angelique Kerber.
In doubles quarterfinals, the top two seeds lost.
The No. 1 tandem of Johanna Larsson and Jasmin Woehr lost to Alize Cornet and Pauline Parmentier, and the No. 2 duo of Andreja Klepac and Tatiana Poutchek fell to Alberta Brianti and Sorana Cirstea.