Warren, who had a double-bogey 6 on the closing hole, had a 4-under 284 total on the Coronado Beach course. He earned $40,000.
``I was really looking forward to competition today,'' said Warren, preparing for the Nationwide Tour season. ``You never really know what to expect at the beginning of a new season.''
Duke also finished with a 71.
Argentina's Juan Abbate (72) finished third at 3 under, and Americans Steve Haskins (72), Jeff Klauk (73) and Mexico's Alejandro Quiroz (71) followed at 2 under.