Vikki finally telling Jake she was leaving him for real and driving off.
Jake gets brutalized by Sugar Ray Robinson but keeps on taking it until the fight is stopped and never goes down.
Well, it's a mix of awesome and Believing His Own Lies since for him, the punishment is more important than winning. The look of disdain which Sugar Ray Robinson gives him says something.
Meta example: Before the making of this movie Martin Scorcese was struggling with a cocaine addiction and was going to give up directing, until Robert De Niro came to him with the script for Raging Bull and encouraged him to direct it, believing that it's themes of self destruction would help him overcome his own problems. Needless to say, Scorcese triumphed over his addiction and would soon become one of the most beloved and respected directors in Hollywood.