Belinda Bencic defeated world No3 Paula Badosa 2-6 7-6 6-4 to move on to the semi-finals of the Charleston Open.
Bencic, the 10th seed, appeared overmatched early on as she won less than half (12-25) of her service points in the opening set, getting her serve broken twice.
But as Bencic found her rhythm with her serve – winning 77 per cent of her first-serve points in the second set (24-31) – she wrestled the momentum away from Badosa, dominating the tie-break before breaking in the opening game of the third frame.
Bencic will face Ekaterina Alexandrova in the semi-final after the Russian dominated Magda Linette 6-0 6-2.
For the match, Alexandrova won 62 per cent of her points on serve (28-45) and 62 per cent of her points on return (26-42).
Fourth seed Ons Jabeur needed just 64 minutes to get the job done 6-3 6-2 against Anhelina Kalinina, winning 81 per cent of her successful first serves (29-36).
Jabeur will play 15th seed Amanda Anisimova in the semi-final after the American cruised past compatriot Coco Vandeweghe 6-1 6-2.
It was not a perfect performance from Anisimova, but she saved all five break points that she faced to never allow her opponent to get close.
Meanwhile, in Bogota at the Copa Colsanitas, top seed Camila Osorio is through to the semi-final after defeating Elina Avanesyan 6-1 6-4, where she will meet Laura Pigossi.