By Miguel Rivera

Former four division world champion Juan Manuel Marquez believes that IBF welterweight champion Kell Brook (36-0, 25KOs) has a shot to pull off a major upset on Saturday night, when he steps in the ring with IBO/IBF/WBC/WBA middleweight world champion Gennady 'GGG' Golovkin (35-0, 32KOs).

The fight, which takes place at the O2 Arena in London, will see Brook jump up by two weight divisions to take the fight at 160-pounds.

Marquez, who last year was targeting  Brook for a world title showdown, is not convinced that everything in the fight will fall upon the issue of weight.

He feels the contest will be a tough fight for both of the involved boxers. If Marquez had to lean to one side, obviously that side would be the heavily favored Golovkin, but he doesn't rule out a victory for Brook.

"He has his chance, of course. At middleweight he looks stronger, heavier. I don't know if that was his strategy or he was just working to get stronger at middleweight. He's going to face a man with great power in his punches. I think it will be difficult for both of them. Brook has better technique and he's a better boxer, but Golovkin is stronger," Marquez said to ESPN Deportes.

"In short, the technical side is much stronger for Kell Brook, but Golovkin has a lot more power. The fight will be difficult, but not so much because of the weight issue. It seems that Golovkin is not someone who gains a lot of weight, but it certainly is a tougher fight for Brook - starting with the fact that GGG is a natural middleweight, throws very powerful punches to the soft parts of the body. But if I had to lean to someone [to win the fight it] would be Golovkin, although, like I said, Brook has a chance."