PRAGUE (AP) — Qualifier Mona Barthel rallied to upset third-seeded Barbora Strycova 3-6, 6-2, 6-3 and advance to the final of the Prague Open on Friday.

Seeking her fourth WTA title, the German faces unseeded Kristyna Pliskova, who defeated Jelena Ostapenko 6-4, 6-2 in the other semifinal.

Big-serving Pliskova was 5-2 up in the second set but faced a break point at 30-40. The Czech served two straight aces — out of a total 17 — before converting her first match point to advance to her second career WTA final. She won her only title last year.

The 82nd-ranked Barthel improved her record against the 18th-ranked Strycova to 4-3.