American wildcard Vania King came from a set down to beat Anne Kremer of Luxembourg in the Pacific Life Open first round on Thursday.
The 19-year-old, who clinched her first WTA title at the 2006 Bangkok Open in her debut season, sealed a 4-6, 6-3, 6-4 victory after a two-and-a-half-hour battle.
King, who next meets 31st seed Tathiana Garbin of Italy in the second round, was sidelined for three weeks last month with a viral illness. "My body isn't 100 percent but I've been trying the best I can," the Californian said.
In other women's matches on Thursday, Germany's Angelique Kerber swept past Russian Ekaterina Bychkova 6-1, 6-2 and Romania's Ioana Raluca Olaru beat Yuan Meng of China 6-4, 6-4.
The top women's players enter the fray on Friday when Australian Open champion and fifth seed Maria Sharapova takes on French qualifier Stephanie Cohen-Aloro and second-seeded Svetlana Kuznetsova faces fellow Russian Ekaterina Makarova.
In the men's event, Swede Robin Soederling crushed Frenchman Sebastien Grosjean 6-3, 6-3 in a first-round match on Thursday and Tour veteran Jonas Bjorkman, also of Sweden, edged past Italian Filippo Volandri 6-3, 7-6.
Russian Dmitry Tursunov defeated Benjamin Becker of Germany 7-6, 6-3 and Belgian Xavier Malisse came from a set down to beat French qualifier Florent Serra 6-7, 6-2, 6-0.
Elsewhere, Belgian Olivier Rochus outplayed Arnaud Clement of France 6-4, 6-4.