Wozniacki, the third seed, remained unbeaten in 19 career matches on the campus of Yale. She defeated Sofia Arvidsson 7-6 (7-4), 6-2 and will face sixth-seeded Dominika Cibulkova in Thursday's quarterfinals.
Cibulkova was a 6-4, 6-1 winner over Andrea Petkovic.
Second-seeded Petra Kvitova advanced with a 6-2, 6-4 decision over Nicole Gibbs. Lucie Safarova will take on Kvitova after overwhelming Zheng Jie 6-4, 6-0.
This hard-court tournament is the final tuneup for next week's U.S. Open.
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