OSTRAVA, Czech Republic (AP)American qualifier Alycia Parks is having quite the breakthrough tournament in Ostrava.

The 21-year-old Parks earned her first win against a top-10 ranked opponent by beating fourth-seeded Maria Sakkari 5-7, 7-5, 7-5 at the Agel Open on Thursday to reach her first WTA Tour quarterfinal.

The 144th-ranked Parks ousted former No. 1 Karolina Pliskova in the opening round – her first win against a top-20 opponent – and showed off her power by hitting 59 winners against Sakkari, compared to just nine for her opponent.

”I came out here not expecting anything, just playing my game, and it got me through the match,” Parks said.

Parks will next face former French Open champion Barbora Krejcikova, who advanced via walkover when Belinda Bencic withdrew with a left foot injury.

Caty McNally, another American qualifier who is playing doubles with Parks in Ostrava, also reached the last eight by beating wild-card entry Karolina Muchova 6-1, 3-6, 6-1. McNally is also into her first WTA quarterfinal and will face top-ranked Iga Swiatek, who advanced Wednesday.

More AP tennis: https://apnews.com/hub/tennis and https://twitter.com/AP-Sports