TOKYO (AP) Japanese wild card Naomi Osaka beat compatriot Misaki Doi 6-4, 6-4 on Monday to advance to the second round of the Pan Pacific Open.

Osaka blasted seven aces against Japan's top-ranked player and converted two of five break chances.

The 18-year-old Osaka, who lost to Madison Keys in the third round of the U.S. Open, awaits the winner between Lucie Safarova and No. 6 seed Dominika Cibulkova.

French Open champion and top-seeded Garbine Muguruza has a first-round bye as does defending champion and second seed Agnieszka Radwanska.

Also, Monica Puig of Puerto Rico overpowered Vavara Lepchenko of the United States 6-0, 6-3.