February 25, 1964: Muhammad Ali wasn't even known as Muhammad Ali when he captured his first heavyweight championship. Cassius Clay was just 22 years old when he defeated Sonny Liston in Miami.

Clay was the No. 1 contender to Liston, but was a 7-1 underdog and the fight outcome was a huge shock. Leading up to the fight Ali engaged in his famous trash-talk. He called Liston an "ugly bear" and saying he would take him to the zoo after the fight. And he famously said he would "float like a butterfly and sting like a bee".

Liston charged out from the opening bell looking for a knockout, but was too slow for the speedy Clay, who began to work his jab. Clay cut Liston for the first time in his career. Clay complained of eye problems but was able to avoid being knocked out. In the 6th round he dominated and Liston didn't answer the bell for the 7th round. Clay won the belt by TKO. At the time, he was the youngest heavyweight champion in history.

Watch the whole fight here:

The two would meet again for a rematch in May 1965 in Lewiston, Maine, in which Clay was now Ali, and where Ali would knock out Liston and retain his belt.

Here's to you Cassius Clay/Muhammad Ali for the day you won your first heavyweight title.

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