Vallellanes, carrying 110 pounds, positioned El Cowboy in second to track the pacesetter before angling out approaching the quarter pole and grabbing the lead entering the stretch in the 5 1/2-furlong race for $6,250 claimers. El Cowboy held sway and finished in 1:01.03.
Competing exclusively at Calder, Vallellanes earned his breakthrough win with his fourth mount.
Javier Negrete trains El Cowboy, who won for the third time in 33 career starts while snapping a five-race winless stretch. Sent off at 7-1 in the six-horse field, the 4-year-old Successful Ways colt paid $16.60, $7.60, and $4.