Muhammad Ali enjoyed several defining moments inside a boxing ring - but when he first became world heavyweight champion, his name was still Cassius Clay.

Brash, cocky and supremely handsome, the young Clay openly challenged and berated Sonny Liston for a chance to fight for the sport's richest prize in 1964.

Most people thought Clay was a lunatic - he was effectively enraging a champion considered invincible by most of the world.

Liston had built his reputation on two first round knockouts of Floyd Patterson - the first won him the title, the second made him a ring monster.

Everything about Liston was ominous - his thick build, his mean, narrow eyes, his two periods in jail and his alleged connections to the Mob.

Apart from his power shows against Patterson, Liston had knocked out other contenders such as Cleveland Williams, Nino Valdes and Zora Folley.

His only loss had come during the early 1950s and even then he had proved his toughness by lasting the distance despite suffering a broken jaw.

Conversely, Clay came into the fight having suffered his greatest humiliation yet - a knockdown courtesy of Henry Cooper's left hook.

Critics understandably predicted doom for Clay, offering the theory that Liston's left hook would wreak bigger damage on the challenger's chin.

In the build-up to the fight, Clay taunted Liston relentlessly, describing him as a 'big, ugly bear' and even driving to his house late at night to continue the insults.

His behaviour was interpreted as the actions of a frightened man, a theory apparently confirmed when his blood pressure was found to be high before the fight.

The venue for the fight was Miami and the date was 25 February, with Clay a huge betting underdog.