Pliskova, ranked 69th, hit nine aces and 28 winners on the way to her first win over her 14th-ranked opponent. It's the eighth clay-court quarterfinal for the hard-serving Czech since she was runner-up in Prague in 2017.
"I feel I'm playing better on clay each year," Pliskova said. "Everybody was saying I cannot move and stuff, but I don't think it's like this. I have more time, so it's good for me that clay is not that fast, I can focus on my game."
The Prague Open is the second European tournament since the WTA restarted amid the coronavirus pandemic, with strict health protocols in place.