TOKYO - Dominika Cibulkova of Slovakia beat defending champion Ana Ivanovic of Serbia 7-6 (5), 6-3 Friday to reach the semifinals of the Toray Pan-Pacific Open.

She will next face seventh-seeded Agniezka Radwanska of Poland, who beat Karolina Pliskova of the Czech Republic 7-5, 6-2. The other semifinal will feature top-seeded Caroline Wozniacki of Denmark and Belinda Bencic of Switzerland.

Cibulkova, the only unseeded player to reach the last eight, showed no sign of the stomach bug that forced her withdrawal from the doubles on Thursday.

She broke back twice in the first set before taking the tiebreaker and then broke twice more in the second to repeat her victory over Ivanovic in the first round of the U.S. Open.

"I had a lot of chances, I just couldn't convert the points today," Ivanovic said. "I felt in both matches she was reading my serve really well, and it was very hard at times to know where to serve, so that's something I'll definitely have to improve on the next time we play."

Earlier, Wozniacki overcame No. 5 Angelique Kerber of Germany 6-2, 2-6, 6-3 after saving five break points in the fifth game of the deciding set.

"That was a long game, and holding that definitely gave me some confidence," Wozniacki said.

Bencic defeated third-seeded Garbine Muguruza of Spain 7-6 (1), 6-1. Bencic saved three straight break points in the fourth game of the second set to hold for a 3-1 lead and swept the next three games to close out the win.