Great rivals will be forever stuck with each other

This is new for football, what it has with Messi and Ronaldo.

For other sports it’s quite the norm. In modern tennis it’s nearly more uncommon than common not to have two all-time greats simultaneously vying for world supremacy: Borg and McEnroe, Evert and Navratilova, Graf and Seles, Sampras and Agassi, Federer and Nadal.

Boxing folklore is similarly defined. Robinson and La Motta; Ali and Frazier; the four kings of the 1980s middleweight division and all their epic tussles for that crown; any golden era for boxing has coincided with having at least one rivalry for the ages.