1. Amir Khan
2. Juan Manual Marquez
Their reason is that Canelo is just about in his prime years and GGG is old and 40 years old. And the body punch will be the key for Canelo if he wanted to soften GGG. And then GGG doesn't look good against Murata although he won that fight.
Not sure if we should listen to this former boxers, but they have their own opinion but we already knew those points already.
We should listen to their opinions with a grain of salt hehe. For me, they are right because Canelo is a body puncher that could hurt anybody in his weight division, how much more if it is against a boxer who is 40 years old which in this sport is considered past his prime.
I have read that article also where Amir Khan and Juan Manuel Marquez predict a knockout win by Canelo but have not read where anyone predicting a win by GGG.
The only consolation for this fight is if GGG survives the full 12 rounds and does not get knocked out, that's where I also put my money come September 17, a Canelo win by decision.
And we have another former boxer who has the same opinion as the majority of them - Carl Framption:
https://www.boxingscene.com/frampton-id-like-golovkin-win-this-decisive-canelo-victory--168999
And as the fight gets closer, we might see former fighters opinion on this fight. But I wouldn't be surprised if they are going for Canelo to win.
Maybe the camp of GGG have seen this reports and will have something to do when the bell rings.
GGG is a good guy, which must be the reason why some of the boxers and boxing experts are withholding their opinions as they respect GGG but deep in their hearts, they know that GGG is on the losing end. Father time is a difficult opponent and no amount of training (at least for me) will make you feel you are years younger. If only the opponent is not Canelo then I could say that GGG has the chance but against Canelo who is trying to bounce back from a loss, it would be tough for GGG.