A feud has developed between the two pound-for-pound kings after Usman, 34, talked up the possibility of a fight.
And while Canelo Alvarez, 31, would be a massive betting favourite against the UFC welterweight champion in the home territory of a boxing contest, Abdelaziz is backing Usman to knock out the Mexican.
Speaking to MMA Junkie, the 44-year-old said: “Kamaru will knock him out in three rounds.
“You cannot say no to Kamaru. He’s a guy who comes from Africa. He jumped a lot of obstacles.
“I believe in Kamaru. This is the difference between me and other people. I believe in him, I live with him, I breathe with him, I die with him, I fight with him. He’s a special person in my life.
“How many street fights have me and Kamaru been to? We’ve been in a lot of street fights, and I have to believe in him. I believe Kamaru can beat any man alive.”
He recently claimed he wants to be paid $100 million to crossover into boxing to fight YouTube star Jake Paul.
But Abdelaziz has insisted his client has no interest in fighting either of the Paul brothers as he only wants to fight the best in the world.
He added: “I know [Usman] didn’t want to fight Jake Paul; he didn’t want to fight Logan Paul.
“He said I’m the pound-for-pound king in MMA, I want to fight the pound-for-pound coward in boxing because I think all these boxers are cowards because none of them want to come to MMA.
“They all want to come to boxing, but at the end of the day, in a street fight, who’s the baddest man on the planet?
“They cannot quote Canelo as the baddest man on the planet. They cannot quote Canelo the pound-for-pound best boxer because if they both in the street, who’s gonna [sic] win? Kamaru would beat his a** like he stole something.”
Usman meanwhile is also absolutely convinced he would beat Canelo in a boxing match.
The 34-year-old, who beat American rival Covington last time, told ESPN: “See that’s the thing about this crazy thing that we do in sports, and not just sports, fighting.
“No one knows the size of the dog inside you – no one knows it.
“When you tell people your plans; yeah they’re not going to believe it because they don’t see it, they can’t see it.
“They don’t do what you do, they don’t walk in your shoes, they don’t walk in your heart and your energy each and every day.
“No one knows that, no one sees it.
“I’ve said everything, I’ve said it, I’ve manifested it.
“I know there’s a lion inside here [points to his chest], a Nigerian African lion that people don’t really understand.”