Sometimes sport becomes much more than a contest of skill to embrace a battle of wills where the contestants dig into their very souls in the pursuit of triumph.
Remember Ali against Frazier in boxing. Now think of Novak Djokovic against Rafael Nadal in the six hour marathon final of the Australian Open.
Soccer players complain about playing two 90-minute matches in a week. Djokovic played games totalling 10 hours in the space of three days and produced tennis of the very highest order throughout. That is the spirit that makes real champions.