One of Kirk Douglas's best early career outings was in 1949's Champion.
I wrote of it:
'At its core, though, Champion- like Raging Bull, is not a boxing movie, merely a film whose structure uses boxing to tell its tale. Midge, like Jake La Motta, is not a nice guy. He’s a user, a liar, and egoist, and a bit of a sadist. We learn, in early scenes with Emma, that he was abandoned as a child, by a father who left and a mother who could only take care of sickly Connie, and grew up in an orphanage. One merely needs to hear the word orphanage to understand the rage that lights Midge’s eyes from the first shots of the film, as well as the few moments he speaks of his hatred for poverty and the condescension it brings. Yet, despite his personal decay, Midge is a savvy guy, realizing that boxing is ‘like any other business, only here the blood shows.’ And it does in this film, as well. If only Ron Howard’s film had such sanguine hues I may have never rediscovered this gem of a film, and bravura performance by Douglas.'
Nailed it again!