Exploring Roberto Duran v Sugar Ray Leonard and the 'No Mas' conspiracies

It's one of the most famous fights in boxing history, but why did Durán ask the referee to stop the fight in the eighth round? If I were to say " Thrilla in Manilla ", most boxing fans would know what I was talking about immediately. If I were to say " the Rumble in the Jungle " the same thing would happen. If I were to mention " the Fight of the Century " there may be a brief moment of