That's UFC superstar Kamaru Usman -- the top pound-for-pound fighter in the sport -- manifesting a super fight with the world's top boxer ... a fight the Nigerian Nightmare tells us could earn him and Canelo over $100,000,000 EACH!

34-year-old Usman hasn't lost in almost 9 years ... and has beat the very best fighters in the world in the Octagon. We're talking Colby Covington (twice), Jorge Masvidal (twice), Gilbert Burns, and Tyron Woodley, just to name a few.

Over the last two years, Usman has made it clear he wants to box Canelo ... pitting the two top P4P fighters against each other.

Until yesterday, 31-year-old Alvarez was dismissive of a fight with Usman, previously telling us he wasn't interested in the fight 'cause he didn't believe it'd add to his resume.

But, seems Canelo had a change of heart on Wednesday ... when Ariel Helwani asked boxing Kamaru, Alvarez answered, "Payday. He wants a payday, I know. But maybe, maybe, why not? You never say no, right?"

Speaking of paydays -- we asked Kamaru how much money the fighters could make ... and he believes it'd be one of the highest-paying combat events ever.

"We talking 9 figures, for sure," Usman says.

But, Usman isn't calling his shot just to inflate his bank account ... he truly believes he can and will beat Alvarez, despite knowing most people will say he can't cross sports and beat the best.

Usman doesn't care.

"Absolutely I see myself winning the fight," Kamaru says, later adding ..."Everything can't be done until it's done."

Canelo has a fight on May 7 against Dmitry Bivol. There's also reportedly talk about a third fight with Gennady Golovkin that would take place in September.

The GGG fight would obviously throw a wrench in Usman's plan to hold the boxing match in September ... but they'd simply have to pick a later date.