ST. PETERSBURG, Russia — Simona Halep withdrew from the St. Petersburg Ladies Trophy on Friday (Saturday, Manila time) because of a knee injury, the same issue she blamed for her opening-round loss at the Australian Open.
The fourth-ranked Romanian had said she was pain-free after her win over Ana Konjuh this week.
Halep was the top seed in St. Petersburg. Her withdrawal sends Russian wild card Natalia Vikhlyantseva into the semifinals, matching her best showing at a WTA tournament.
Vikhlyantseva, ranked 115th in the world, will next play Kristina Mladenovic, who beat defending champion Roberta Vinci, 6-1, 6-4.
Also, second-seeded Dominika Cibulkova advanced by beating fifth-seeded Elena Vesnina, 6-3, 6-3.
The Slovak will face Yulia Putintseva of Kazakhstan, who surprised third-seeded Svetlana Kuznetsova, 6-3, 6-7 (4), 7-5.