By TMZ Sports

Larry Merchant WON'T be watching Floyd Mayweather fight Andre Berto on Saturday night ... because the legendary boxing commentator says that any Mayweather fight that doesn't involve a higher level of opponent of middleweight champion Gennady Golovkin is a total waste of time.

Merchant was out in L.A. recently when we, of course, had to ask for his expert opinion on the fight in Vegas this weekend.

That's when Merchant WENT IN on Floyd ... saying he won't watch because Berto is not a "serious opponent," saying that Floyd is afraid to fight the guy everyone wants to see him battle ... GGG.

He also said there are at least six other fighters in the welterweight division who were more worthy of the opportunity.

"I didn't even know that was happening. Why would anyone watch that kind of a fight?," Merchant said. "Berto has lost three of his last six fights. There are a lot better potential serious opponents. I think serious fight fans are asking themselves - why?"

"The most interesting fight would be Golovkin. But he's afraid of Golovkin so he's not going to fight him. But there half a dozen other really good, young welterweights who might give him a little bit more trouble than he wants right now."