FBI suspected that Ali's KO of Liston was fixed

[Master]

I would normally think that punch by Ali would not knock down Liston. However if you watch the tape, Sonny gets back up and continues to fight. It was only when Natt got involved and told the ref to stop it that Liston stopped fighting. Therefore I think it was a legitimate punch.

You must be thinking of the first fight?

No that was the second fight