#4 Joan Guzman:
Our next amateur flop turned professional champion, hails from the tiny island of the Dominican Republic. The flyweight category in the Atlanta Olympics of 1996 saw two of the most talented boxers of that generation square off against each other in the first round itself.
Joan Guzman faced off against Omar Narvaez of Argentina, both having excelled in the amateur circuit prior to the Olympics. Guzman lost a well-contested bout to Narvaez and had to exit the competition in the first round itself.
In comparison to the others on this list, Guzman had a relatively long amateur career. Towards the fag end of it, he looked to be struggling to make weight. When he made his debut on the professional circuit in 1997, he weighed 124 pounds.
Guzman went on to have a successful career on the pro circuit, where he established himself as the world champion in the flyweight category. Omar Narvaez too became the flyweight champion in professional boxing, some years later.