(Reuters) - Slovakia's Dominika Cibulkova beat defending champion Samantha Stosur 6-4 6-3 on Thursday to reach the Strasbourg international semi-finals where she will face fourth seed Mihaela Buzarnescu.
Romanian Buzarnescu beat Taiwan's Su-Wei Hsieh 6-0 6-3.
Fifth seed Cibulkova hit 21 winners to her 10 unforced errors to oust Australian Stosur in just over 90 minutes to reach her second semi of the season ahead of the French Open.
Top seed Ashleigh Barty is also in the last four for the first time after the Australian beat China's Wang Qiang 7-5 6-4.
Barty stormed back from a break down in the second set to win the last three games in a row to set up a semi-final clash with third seed Anastasia Pavlyuchenkova of Russia.
"I think it was a very tough match right from the first point," Barty said. "I felt very clean off the ground today and felt like that was my best match so far this week."
Pavlyuchenkova saw off Kazakh Zarina Diyas 6-4 6-2 with a disciplined effort, converting all five of her break points.
"It feels great because this season hasn't been easy for me," Pavlyuchenkova said. "At the start of the year I was struggling a lot with my shoulder. I still do, but it's much better."