Manfredy, nicknamed El Diablo (The Devil) because of his reckless lifestyle and of his boxing style[1] converted to Christianity after trying to commit suicide in his bed while on cocaine.

[4] Manfredy was known for his walk-ins to his matches wearing a latex mask depicting Satan, which he used until his fight with Floyd Mayweather and conversion to Apostolic Pentecostalism.

A frequent contender, Manfredy was a former WBU Super Featherweight champion, but lost in each of four attempts to capture a World Title.

Following this fight, Manfredy knocked out Ivan Robinson in what had been HBO's Boxing After Dark's highest-rated show of 1999.

In 2017 Manfredy took a position as a trainer and promoter in Crown Point, Indiana in a gym owned by boxer Ricky Carr.