By TMZ

Former welterweight world Andre Berto is totally down to take on the winner of a fight that doesn't exist yet ... saying he'd gladly take on the victor in the Saul 'Canelo' Alvarez vs. Gennady Golovkin mega-fight ... if it ever happens.

We got Berto out in Beverly Hills and asked him about the fight ... which is the biggest fight out there in boxing and who he thinks would take it.

Berto thinks Golovkin would be too much for Canelo but whoever wins - he wants to fight that guy.

He feels Canelo's decision to vacate the WBC middleweight championship was a "business" to push back a mandatory fight with Golovkin. The WBC had ordered Canelo to face GGG in the fall and a purse bid was scheduled for May 24th in Mexico City.

"I think it was a business move [for Canelo to vacate the title]. A business move to make that money and I don't think that he feels it time for the GGG fight yet. I think GGG needs him, he doesn't need Golovkin. Canelo is going to make money regardless, whether it's with GGG or not. I probably pick GGG to win," Berto said.

"I would definitely like to fight the winner,  because it would come with that check. I fought at 160 in the amateurs so that wont be too bad [moving up to middleweight]."