Serafim Todorov from Bulgaria was the last person to beat Foyd Mayweather in the ring and it happened few month before the American turned professional
The victory by Todorov, then 27, over Mayweather, then 19, in the featherweight semifinals of the 1996 Olympic boxing tournament was the last time Mayweather lost in the ring.
A few months later, Mayweather turned professional and began a career that has produced 47 consecutive victories and hundreds of millions of dollars in earnings.