Top seed Agnieszka Radwanska was among Wednesday's quarterfinal winners at the Sydney International, a final Australian Open tune-up.

The world No. 4 Pole, the 2012 Wimbledon runner-up who was last week's champion in Auckland, got past Italian Roberta Vinci 6-4, 7-5 at Sydney Olympic Park Tennis Centre. Radwanska will face fourth-seeded Chinese slugger Li Na in Thursday's semifinals.

The equally as hot sixth-ranked Li, fresh off her season-opening title in Shenzhen in her native China last week, came from behind to beat American qualifier Madison Keys 4-6, 7-6 (7-2), 6-2 in 2 hours, 20 minutes on Day 4.

Li is seeking a trip into a third straight Sydney final, as she was the 2011 champ here and lost to reigning world No. 1 Victoria Azarenka in last year's title tilt.

Thursday's other semifinal will pit second-seeded German left-hander Angelique Kerber against diminutive Slovak Dominika Cibulkova. Kerber downed qualifier, former top-five star and 2008 Sydney runner-up Svetlana Kuznetsova 6-3, 7-5, while Cibulkova upset third-seeded French Open runner-up Sara Errani of Italy 6-2, 6-1.