Top-seeded Simona Halep cruised into the semifinals of the Transylvania Open on Friday, but US Open champion Emma Raducanu lost to a fellow teenager in less than an hour.
The third-seeded Raducanu lost 6-2, 6-1 to 19-year-old Marta Kostyuk of Ukraine after struggling with her serve throughout the match. Raducanu double-faulted seven times and won less than half the points in her service games as Kostyuk advanced to her third semifinal of the season.
READ: Van de Zandschulp stuns Rublev in St. Petersburg quarters
Kostyuk will aim to reach her first career final when she plays Halep, who eased past fellow Romanian player Jacqueline Cristian 6-1, 6-1.
No. 2-seeded Anett Kontaveit also had a smooth path into the semifinals, beating Anhelina Kalinina of Ukraine 6-3, 6-1 for her 13th straight indoor win, following titles in Ostrava and Moscow.
The win kept the second-seeded Estonian in the race for the season-ending WTA finals next month.
Kontaveit will play Rebecca Peterson of Sweden, who edged Lesia Tsurenko of Ukraine 6-2, 3-6, 6-3.