10. Betrayed
In an autobiography written in the 90s, George Foreman claimed he lost to Muhammad Ali in the Rumble in the Jungle because he had seen a friend in the crowd, mid-bout, cheering for Ali. Bemused by the betrayal, Foreman claimed he could no longer concentrate and that is why Ali was able to knock him out in the eighth round. It should be noted that Foreman has since come to terms with the loss and openly admits he was beaten by the better man.