Second seed Caroline Garcia was shocked at the Ladies Open Lausanne on Wednesday, downed in straight sets by Bernarda Pera.
Pera, ranked 85th in the world, proved too strong in a 6-2 6-4 victory to set up a quarter-final meeting against Xinyun Han.
The left-hander won the last five games of the first set and never looked back and said afterwards her second serve was key.
"You can say I'm satisfied. I played well," Pera said.
"She's a tough opponent and I'm thrilled to be in the next round. I think she was struggling a lot with my second serve.
"I was able to break her a couple of times and that's what made the difference."
Han beat Liudmila Samsonova 7-5 6-4, while Australian Daria Gavrilova was another big name beaten at the event, Russian Natalia Vikhlyantseva toppling the seventh seed 6-3 6-2.
Vikhlyantseva will play third seed Alize Cornet in the last eight, the Frenchwoman coasting to a 6-1 6-1 success against Jasmine Paolini.
Also on Wednesday, Laura Siegemund and Kristyna Pliskova won at the Bucharest Open.
Sixth seed Siegemund defeated Lara Arruabarrena 7-5 6-3 and Pliskova did it even easier, cruising past Ysaline Bonaventure 6-0 6-2.
Martina Di Giuseppe came from behind to topple Varvara Lepchenko 3-6 6-1 7-6 (7-3) and Irina-Camelia Begu beat Kaja Juvan 6-4 6-3, while Viktoria Kuzmova defeated Jaimee Fourlis 7-5 6-2 in the late match.