Alfonso beat Newfel Ouatah but lost to Russian Evgeny Romanov at the world junior championships 2004 (semifinal).

He became the Cuban #1 only after Solis (who had gone up in weight, too) defected and he beat veteran Michel López Núñez in the National Championships 2007 and 2008.

He immediately won a major title, in the Pan American Games in Rio, beating Brazilian Antônio Rogério Nogueira 4:0 in the semis and Colombian Oscar Rivas 8:4 in the finals [1].

His winning continued into 2017 with a first-round TKO over Keith Thompson at the BJCC in Birmingham, Alabama on the undercard of Deontay Wilder vs. Gerald Washington on February 25.

The fight took place in Tuscaloosa, Alabama, and the winner was to take home the vacant USBA Southern Region Heavyweight Title sanctioned by the IBF.