Greatest boxer under 20 years old?

They start them early in Mexico, for sure. Canelo was 15 when he made his pro debut and was 26-0-1 by the time of his 19th birthday.

benitez - won the title against a top10 ever at the weight and defended it 2 times, undefeated at 20 canzoneri - a draw and a loss for the bantamweight title (promptly avenged at featherwight), 2 wins and a loss for the featherweight titles (well past prime dundee and prime bass) it's between these two. more fights with losses or great achievement without losses. it's subjective.

Right now, there's this Mexican kid (maybe at 130). I think he was under twenty the last I saw him. I forgot the name. He's a destroyer. Very special and entertaining.

Benitez won a world welterweight title, Ali beat an admittedly old Archie Moore at around 20, but it was still Archie Moore....beyond that I'm not too sure. Somebody mentioned Canzoneri who I think won a world title by 20 but it is difficult to gauge the quality of his opponents in those early days. An obvious shout would also be Tyson who beat some big, top quality heavyweight while he was still 18, 19 and 20.

Go to Mexico them dudes at 13 will slap up fools

I would go with Tony Canzoneri