Roar Emotion led every step of the way, and held off a late charge from Fircroft, to take the Black-Eyed Susan Stakes (gr. II) by a half-length Friday at Pimlico.
Santa Catarina, favored at 4-5, ran third, 8 1/2 lengths farther back.
Austin's Mom and Holiday Lady were scratched, leaving a field of eight to contest the $200,000 race.
Under John Velazquez, Roar Emotion set all the fractions in the nine-furlong race -- :23.20, :47.71, 1:12.23, 1:38.21 and 1:52.33. The race was run on a very sloppy track.
Roar Emotion, a 3-year-old Roar filly, is owned by Joe Allen and trained by Carlos Martin. She was bred in Kentucky by Brenda Jones.
Santa Catarina broke sharply, but Stevens took a hold and Roar Emotion went to the front while the favorite settled behind, then got stuck wide of the leader in fourth place.
Santa Catarina tried to make a run at Roar Emotion, but the winner put her away and then held off the late-charging Fircroft under Pat Day. Fircroft had one beaten into the final turn, but made a strong bid along the rail in the stretch.
"There were a lot of things wrong with this filly," said Martin of Roar Emotion. "She's a big filly and needed time to mature, and we needed patience getting her to the races. The owners are really good about these things and always insist that I try to do the right things with the horse. She has speed and we had the right horse, the right distance and the best jockey in the world. We were getting tired at the end but she really held on and got the job done."
Bob Baffert, who trains Santa Catarina, offered no excuse.
"She looked and acted great in the paddock, but I knew she was in trouble at the quarter pole. We had a pretty wide trip, but I don't know why she didn't finish stronger."
Roar Emotion paid $8.80, $5.40, and $2.80, while Fircroft returned $11.60 and $3.20. Santa Catarina, ridden by Gary Stevens, held third, paying $2.10. The exacta was $109.80 and the trifecta $249.60. Ivanavinalot, the 5-2 second choice, finished fourth, another 5 ¾ lengths back.
Roar Emotion has now won three of her five lifetime starts. She had been out only once this year, finishing second to Cyber Secret in the March 22 Cicada (gr. III). The winner of the Demoiselle (gr. II) at Aqueduct in November earned $120,000 for the victory, and has now earned $298,260 in her career.