
Kostyuk, who dumped out four-time champion Iga Swiatek in the last 16, beat Svitolina 6-3, 2-6, 6-2 and goes on to face Russian teenager Mirra Andreeva on Thursday for a place in the final.
“I’m very happy I found a way. It was very difficult in the first two sets,” said Kostyuk.
The 23-year-old Kostyuk extended her unbeaten run on clay this season to 17 matches. She is bidding for a third title on the surface after wins in Madrid and Rouen.
“I still think it’s very far. I still have two matches to play,” added Kostyuk.
Svitolina fell at the quarter-final stage at Roland Garros for the sixth time. It is the only major where she has not reached the last four.