Eugenie Bouchard reached the semi-finals at the Nurnberger Versicherungscup but top seed Angelique Kerber is out after losing to Karolina Pliskova.
The German went down 7-6 (7/5) 6-4 while Bouchard battled to a 7-6 (7/3) 7-6 (8/6) victory over Yaroslava Schevdova.
It was Pliskova's first victory over a top-10 player and even more impressive considering she won just one of the first 17 points.
The Czech said on wtatennis.com: "She was playing really amazingly in the beginning and there wasn't very much I could do. But then I won one game and suddenly I started to feel much better and I came back to win the first set.
"I sensed she was a little bit down at the start of the second and I made a really fast start.
"I then started to make a few mistakes that perhaps I shouldn't have and made it a little bit complicated. I'm happy that I got through in the end."
Seventh seed Caroline Garcia was also dumped out, the fast-rising Frenchwoman losing 6-7 (9/11) 6-4 6-4 to Italy's Karin Knapp, but fourth seed Elina Svitolina beat Mona Barthel 6-4 6-4 to advance.