Jelena Ostapenko continued her dominance over Iga Swiatek with a three-set victory to reach the Stuttgart Open semi-finals.

Latvia's Ostapenko beat world number two Swiatek 6-3 3-6 6-2 to extend her unbeaten winning streak against the Pole to six matches.

Ostapenko is the first player to beat five-time major champion Swiatek on every surface - once on grass, four times on hard courts and now once on clay.

"She's a great clay-court player but I won the French [Open] as well, so I can say the same thing about myself, " the 27-year-old said.

"I have so much respect to her and her team but every time I step on the court with her, it's a battle and I'm ready for it."

Ostapenko will face a semi-final against Russia's Ekaterina Alexandrova, who beat third seed Jessica Pegula 6-0 6-4.

World number one Aryna Sabalenka, who reached the quarter-finals without playing a match after opponent Anastasia Potapova withdrew with injury, faces Elise Mertens later on Saturday, before Coco Gauff plays Jasmine Paolini.