Tokyo: World No.1 Victoria Azarenka beat Italy`s Roberta Vinci to enter the quarterfinals of the Pan Pacific Open tennis event here Wednesday.
The Belarusian star had little problem dispatching the 14th seed in a 6-4, 6-2 victory in the third round.
In the quarters, the U.S. Open finalist will face Germany`s fifth seed Angelique Kerber, who breezed past Urszula Radwanska of Poland 6-1, 6-1.
Kerber will seek her first win in three encounters against Azarenka.
Third-seeded Agnieszka Radwanska, meanwhile, outdid her sister to knock out U.S. qualifier Jamie Hampton 6-4, 6-3.
In the next round, the 23-year-old Pole will meet 10th seed Caroline Wozniacki of Denmark.
Wozniacki had to dig deep to oust Li Na, seeded 7, surging back after losing the first set 4-6, 6-3, 6-4.
Elsewhere, second-seeded Maria Sharapova defeated Lucie Safarova of Czech Republic 6-2, 7-6(5) to reach the quarterfinals, where she will play eighth seed Sam Stosur.
The 28-year-old Australian player eliminated Slovakia`s Dominika Cibulkova 6-4, 7-5.
The last quarterfinal pair will see Sharapova`s compatriot Nadia Petrova playing against Italy`s Sara Errani.
Petrova, seeded 17, struggled past Croatia`s Petra Martic, racking up 15 aces to snatch a 7-6(2), (1)6-7, 6-4 win.
Sixth-seeded Errani had nearly as difficult a test in her third-round match against France`s Marion Bartoli, pulling out the match from one set down 3-6, 6-2, 6-2.