The 5-year-old Bowman's Band mare, racing wide all the way from the No. 11 post position, went to the lead at the top of the stretch under Rajiv Maragh, and Judy the Beauty, closing on her outside, could not quite reach equal terms. Dance Card finished third.
The 7 furlongs over the fast Santa Anita main track took 1:20.75.
Groupie Doll was a dominant force coming to last year's Breeders' Cup, riding a four-race winning streak. This year, she had only one previous win in three starts for trainer William Bradley and finished third behind Judy the Beauty in her last start, the Grade II Thoroughbred Club of America, over the Keeneland all-weather track.
The victory was her 11th in 21 starts and moved her career winnings past the $2 million mark. She is scheduled to be sold at auction this month.