Top seed Kiki Bertens will face American teenager Coco Gauff in the Linz Open quarterfinals on Friday.
The Dutchwoman beat Alison Van Uytvanck of Belgium 4-6, 6-3, 6-3, on Thursday, while no. 8 seed Ekaterina Alexandrova got through to the quarterfinals after beating Germany's Laura Siegemund in Austria.
Ekaterina Alexandrova, 24, edged Siegemund 7-6(1), 2-6, 6-4 in a closely fought contest that saw five broken serves during a tense final set.
The Russian will be looking to go one better than her last Linz Open appearance, having finished runner-up to Camila Giorgi of Italy in last year's tournament.
Alexandrova will face Kristina Mladenovic of France, after she beat no. 4 seed Donna Vekic of Croatia 3-6, 6-1, 6-2 in the second round.
In the other half of the draw, compatriot No. 9 seed Anastasia Pavlyuchenkova was upset by Viktoria Kuzmova of Slovakia 6-2, 2-6, 6-4.