Starsalot, a winner only once in 20 previous races during the past two years, sloshed through the mud to a 10 1/2-length victory in the $35,000 feature race Thursday at Santa Anita's Oak Tree meeting.
Jockey Martin Pedroza took Starsalot to the front immediately and began pulling away from the field in the turn for home.
The race was scheduled for the turf course but was shifted to the main track because of heavy afternoon rain.
Only four horses ran in the feature, and the 5-year-old Starsalot, at 8-1, was sent off at the longest odds by the crowd of 12,866.
The 7-10 favorite, Magna Plus, finished last after falling behind early and spent much of the race bucking through water splashed up by the horses ahead of him.
Dark Promise, ridden by Fernando Toro, was second, and it was another seven lengths back to Good Thought Willy, with Fernando Toro aboard. Magna Plus was another 1 lengths behind.
Starsalot was timed in 1:52 3/5 for 1 1/8 miles and paid $18.80 and $6. Dark Promise paid $4 to place.