In the novel it says they fought alot.Not that Santino literally kicked the living shit out of Michael.Even Michael replies"i finally got used to you beating on me ,know i have to get used to this?"

The hero and the coward both feel the same thing, but the hero uses his fear, projects it onto his opponent, while the coward runs. It's the same thing, fear, but it's what you do with it that matters. Cus D'Amato