Dominika Cibulkova of Slovakia defeated Spain's Anabel Medina Garrigues 6-3, 7-6 (3) on Sunday in the first round of the Pan Pacific Open.
The 12th seeded Cibulkova improved to 4-1 in head-to-head matches between them after dispatching the unseeded Garrigues in 1 hour, 36 minutes at Ariake Coliseum.
In other first round matches, 14th-seeded Roberta Vinci of Italy beat Barbora Zahlavova Strycova of the Czech Republic 6-4, 4-6, 7-5 while Serbia's Jelena Jankovic overpowered Belgium's Yanina Wickmayer 6-3, 6-3.
Top-ranked Victoria Azarenka has a first-round bye as does second-seeded Maria Sharapova. The $1.2 million tournament features 12 of the top 13 players in the world rankings.