That's Ali Abdelaziz, Kamaru Usman's manager, telling TMZ Sports he wants to answer the question, who's really the top pound-for-pound fighter in the world, by boxing Canelo Alvarez, the best pugilist in the world.

And, he believes his guy can, and will, win.

The 34-year-old welterweight champ is rematching Colby Covington at UFC 268 in November, but after that fight, Ali has his sights set on 31-year-old Alvarez.

"Let's get the pound-for-pound king in boxing vs. the pound-for-pound king in MMA. We're not into this fake fight, gimme fight," Abdelaziz says.

"If you think you're the pound-for-pound king, Kamaru is the pound-for-pound king. Let's have 2 kings fight each other. No takedowns allowed."

FYI, Canelo-- the super middleweight champ -- hasn't lost in 8 years ... since his fight with Floyd Mayweather in 2013.

But, beating Alvarez isn't all Ali has planned ... he says he then wants his fighter to go to 185 lbs. (from 170 lbs.) and fight Israel Adesanya.

"After [Canelo,] I've always said it, I want Kamaru to go up a weight class and fight for Middleweight title. I believe that today Kamaru can go up and be 2 division champion."

It's a tricky fight to make ... Usman and Adesanya have been resistant to even talking about a fight against each other because of their shared connection to Africa. Both men were born in Nigeria.