After tracking the leaders under jockey Rajiv Maragh, Groupie Doll came three-wide into the stretch, easily ran by Dust and Diamonds and drew off without much encouragement, winning by 4 1/2 lengths. Dust and Diamonds held second and it was a long way back to Switch in third.
Last year's winner, Musical Romance, attended the pace but faded late to finish well up the Santa Anita main track.
Groupie Doll, a 4-year-old Bowman's Band fill, ran the 7 furlongs on a fast track in 1:20.72.
She started her winning streak in April at Keeneland and continued with wins at Churchill Downs, Presque Isle Downs and back at Keeneland -- all graded stakes.
"Every race just keeps getting better," Maragh said after Saturday's win.
Dust and Diamonds came to the Breeders' Cup with a three-race winning streak, compiled at Oaklawn, Delaware Park and Belmont.