Hopkins is the one guy that I think would be able to outbox Monzon at middleweight over the course of an entire fight. Tough enough to where I doubt Monzon would stop him, Smart enough to work around Monzon's strengths, wouldn't be at a size disadvantage, and would have a handspeed advatage.
Sad thing is that Carlos Monzon refused to learn the English language, he usually defended his title in places like Monte Carlo, Monaco, Paris, France, Buenos Aires, Argentina and Rome, Italy. He fought here once in June 1975, defeating challenger Tony Licata by TKO 10 in Madison Square Garden. The taxes ate up most of Monzon's purse so he elected to continue to fight in Europe. Carlos was not one of those type of fighters to get riled by a boastful opponent, he took care of business in the ring, it was not personal but business, he was undefeated in his last 82 bouts, so pride and confidence played a huge role. Monzon also kayoed 61 of his opponents, so he could hit.