A native of Trujillo Alto, Puerto Rico, the 10-pound apprentice moved to South Florida and learned his trade at Gulfstream Park West.
"The trainer told me I was riding the best horse," Medina said through an interpreter. "The horse responded for me really good. He ran a very good race. I'm very happy. It feels very good to win the race."
The Daniel Gazader-trained Sir Hannoun relaxed under Medina while setting an uncontested pace in the 1 1/16-mile $6,250 claiming race. Encouraged by a couple of right-handed taps of the whip, the 4-year-old Autumn Music gelding drew off in the stretch to score by 3 3/4 lengths.
Medina, who registered a second- and a third-place finish during the current Gulfstream meet, won his first race on his 19th mount, earning the traditional barrage of water and soap from his fellow riders on his way back to the jockey's room.