Former champion Petra Kvitova has withdrawn from the St. Petersburg Ladies Trophy because of illness.

The 29-year-old Czech had been due to play Ekaterina Alexandrova in the quarterfinals but 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,” the third-seeded Kvitova said.

With the walkover win, Alexandrova, the WTA Shenzhen Open champion, will now play either second-seeded Kiki Bertens or qualifier Anastasia Potapova in the semifinals.

Also on Friday, Elena Rybakina beat Oceane Dodin 6-7 (7-5) 7-5 6-2. Rybakina will next face either Belinda Bencic or Maria Sakkari.