Canelo Alvarez vs. Jermell Charlo preview: The history books and odds are against the younger Charlo twin in this clash of undisputed champions... but is the crown beginning to slip for boxing's king?

There are plenty of unanswered questions swirling around but what is certain: over 16 years and 38 fights, Charlo's mind has never had to picture a challenge this stiff or a prize this great.