I can only think of Muhammad Ali getting up in the 15th round in the first fight with Joe Frazier or Larry Holmes getting up after that shotgun overhand Right by Ernie shavers to win not just a fight but the round itself or at least even it up

This is what all time greats are made of. It's not just boxing skills or punching power but it's also the ability to withstand anything from one of the most devastating punchers of all time in the heavyweight division,

https://youtu.be/Lg2uQ1uoBJU?si=5yZ07xarS5Ali7cM