The Gentleman from Arizona (1939)

The "gentleman" is played by John King, but the star of the show is J. Farrell McDonald, cast as a chronic gambler named Coburn. When the old man loses every penny he has, wandering cowboy Pokey (King) comes to the rescue by grooming a wild stallion for a successful racetrack career. Everything comes to a head during the climactic Big Race, with the expected (but still satisyfing) results. Ruth Reece and Joan Barclay share the leading-lady responsibilities, while the villainy is in the capable hands of Monogram's ace utility actor Craig Reynolds.

Unfortunately the movie The Gentleman from Arizona is not yet available on HBO Max.