Undefeated professional boxer Floyd Mayweather Jr. announced his retirement after knocking out MMA Champion Conor McGregor in the 'richest fight in history'. "I chose the right dance partner for my last dance... this was my final fight," said Mayweather. The American ends his career with an unbeaten 50-0 professional record, surpassing former boxer Rocky Marciano's 49-0 career record.