Third-seeded Samantha Stosur of Australia defeated Johanna Larsson of Sweden 6-4, 6-2 on Monday to advance to the second round of the Japan Women's Open.
In other first-round matches, seventh-seeded Monica Puig of Puerto Rico beat defending champion Heather Watson of Britain 6-4, 6-4.
Fifth-seeded Eugenie Bouchard of Canada beat Varvara Lepchenko of the United States 6-3, 6-0.
Top-seeded Jelena Jankovic pulled out, citing a left-hip injury. The Serbian player received medical treatment in the second set of her 6-2, 6-2 loss to Serena Williams in Sunday's final of the China Open in Beijing.