Arcadia, CA - Leading 3-year-old filly Untapable, trained by Steve Asmussen, rallied through the stretch to win Friday's $2 million Breeders' Cup Distaff at Santa Anita Park to cap the first day of racing in the 31st World Championships.

Ridden by her usual jockey Rosie Napravnik, Untapable raced wide through much of the 1 1/8-mile race. Sent off as the 8-5 favorite in the 11-horse field, Untapable drew along side Iotapa for the lead on the final turn.

Untapable, winner of this year's Kentucky Oaks, took the lead at the top of the stretch and was clearly the best horse. The filly posted a 1 1/4-length win over 6-1 third pick Don't Tell Sophia.

"She's so amazing," Napravnik said immediately after the win. The jockey later announced her retirement from riding to start a family with her husband.

Finishing third was Iotapa followed by 2013 Juvenile Fillies winner Ria Antonia and 50-1 longshot Unbridled Forever. Last year's winner Beholder, a two-time Eclipse Award winner, was unable to defend her crown after recently spiking a fever.

Untapable covered the 1 1/8 miles in 1:48.68 on a fast track.

Owned by Winchell Thoroughbreds, Untapable earned more than $1 million with the win and reaches $3 million in career earnings. The filly has won eight of 11 lifetime starts, six of seven this year.

Untapable returned $5.20, $3.40 and $2.60. Don't Tell Sophia paid $4.60 and $3.40, and Iotapa paid $4.00 to show.