Petra Kvitova withdrew from the St. Petersburg Ladies Trophy on Friday because of illness.
The third-seeded Kvitova had been due to play Ekaterina Alexandrova in the quarterfinals. Kvitova said the unspecified illness had bothered her during Thursday's three-set win over Alison van Uytvanck.
“I wasn't feeling well during my match yesterday and hoped I would feel better today, but unfortunately, that's not the case," Kvitova said.
With the walkover win, Alexandrova will play either second-seeded Kiki Bertens or qualifier Anastasia Potapova in the semifinals.
Also Friday, Elena Rybakina beat Oceane Dodin 6-7 (5), 7-5, 6-2. Rybakina will next face either Belinda Bencic or Maria Sakkari.
