The Contender (1944)

In order to get some extra money to send his son to military school, a truck driver turns amateur boxer. His success in that field convinces him take up the sport full-time, and he soon fights his way up to where he becomes a contender for the Heavyweight Championship. However, his chance at the title is endangered when he starts squiring around a flashy blonde and begins tasting the "good life" of nightclubs, partying and booze.