Davenport hadn't played singles tennis since last September and had one doubles match since the birth of her son in June. But she had little trouble in a 6-2, 6-2 rout of fifth-seeded Eleni Daniilidou in first-round play of the hard-court tournament.
Davenport next faces Julie Ditty, who was a 6-2, 6-1 winner in her first-round match with Hana Sromova.
Eighth-seeded Yaroslava Shvedova was routed by qualifier Meng Yuan, 6-0, 6-1, in another first-round upset.
Three seeded players managed to advance. No. 3 Patty Schnyder stopped Shuai Zhang, 6-4, 6-2; fourth-seeded Anabel Medina Garrigues beat Sandy Gumulyz, 6-1, 6-1; and No. 6 Martina Muller top Tatiana Poutchek, 6-3, 6-3.
The winner of the Commonwealth Bank Tennis Classic will collect $32,340.