Barbora Krejcikova extended her unbeaten run on European indoor hard courts to reach the Prague semifinals, while 16-year-old qualifier Tereza Valentova upset defending champion Marie Bouzkova.

Krejcikova defeated compatriot Dominika Salkova 6-3, 6-3 in one hour and 20 minutes to advance to the last four of the WTA 250 event. The second seed, who won the title in Athens the previous week, has now gone undefeated on European indoor hard courts across both tournaments.

In a surprise result, Valentova eliminated reigning champion Bouzkova in the quarterfinals. The 16-year-old, ranked 117th, came through qualifying to reach her first WTA semifinal.

Krejcikova’s victory over Salkova was straightforward despite her opponent’s qualifying run, while Valentova’s breakthrough performance marks a significant career milestone for the teenager.