Timea Babos of Hungary secured an upset 6-2, 5-7, 7-5 win against third-seeded Flavia Pennetta of Italy to reach the Grand Prix SAR semifinals on Thursday.
In an error-strewn match featuring nine double faults and 12 service breaks, Babos broke Pennetta's serve seven times to set up a last-four clash with Frenchwoman Kristina Mladenovic, who eased past Laura Arruabarrena of Spain 6-4, 6-1.
Although Mladenovic dropped serve twice in the first set, she did not concede a break-point chance in the second set, in which she broke Arruabarrena's serve twice.
Also, fourth-seeded Elina Svitolina of Ukraine beat Karin Knapp of Italy 6-0, 3-6, 6-3 to set up a semifinal against either second-seeded Timea Bacsinszky of Switzerland or seventh-seeded Anna Karolina Schmiedlova of Slovakia.
They were playing later Thursday.