Top-seeded Karolina Pliskova advanced to the Prague Open semifinals by beating fellow Czech and wild card Denisa Allertova 6-2, 5-7, 6-1 on Thursday.
The 14th-ranked Pliskova made three breaks in the final set and converted her first match point with a backhand return winner to beat Allertova in their first encounter.
Pliskova took the first set with one of her 10 aces before the 103rd-ranked Allertova rallied, converting her fifth set point to win the second set.
On Friday, Pliskova will play Yanina Wickmayer of Belgium, who rallied from a set down to defeat qualifier Danka Kovinic of Montenegro 2-6, 6-3, 6-3.
Unseeded Katerina Siniakova beat another Czech, third-seeded Barbora Strycova 6-4, 6-2, and will next face qualifier Lucie Hradecka, who defeated wild card Klara Koukalova 7-5, 4-6, 7-5 for her first win in five meetings between the Czechs.
The 18-year-old Siniakova, ranked 76th, clinched her second semifinal appearance on the WTA tour.
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