Can you imagine what a prime GGG would do to a 35, 36 and 40 going on 41 y/o Ginger? There wouldn't be any need for even one rematch because Big G would administer such a X-rated biblical shellacking to him no commission on the planet would sanction another fight between them ever again.
They know each other well this will be their 25 round both men could take a punch probably SD the good is Oscar is not involved the bad Vegas got Canelo as favorite so GGG needs a KO to win the fight.
Your last sentence is what it is all about. No one knows how GGG is going to approach this fight. If he boxes, plays it safe and just goes out with an L and a bag of cash then Canelo isn't taking him out head or body. You could argue GGG thinks he outboxed Canelo both fights and feels that since Canelo lost a decision in his last fight that he too can get a decision. We just don't know.
You know, I've heard of a lot of nicknames for Canelo. The red mouse, the ginger, clen, mofo (by Plant), canela (by Bivol) as well as clenelo which seems to be the most popular one, but I don't think ever heard of roidelo before.