Second seed Caroline Wozniacki came from behind to defeat Bulgarian qualifier Tsvetana Pironkova 3-6 6-3 6-4 and set up a third-round tie with Russia's Maria Kirilenko.
Former Wimbledon champion Maria Sharapova begins her campaign on Wednesday against American qualifier Lilia Osterloh, while second seed Jelena Jankovic is first up against Bulgaria's Tsvetana Pironkova.