On Saturday, Usyk, 35, faced an improved Joshua but outboxed him once again to retain his WBA, WBO, IBF and IBO titles.
"I give this victory to my country, to my family, to my team and to all the military who are defending the country," Usyk said after win the "Rage on the Red Sea" bout.
He then turned his attention to rival heavyweight world champion Tyson Fury, who announced his latest retirement earlier this month but has signalled his willingness to resume his career.
Victory over Fury would unite all four heavyweight belts and make Usyk the undisputed champion.
"I'm sure that Tyson Fury is not retired yet," Usyk said. "I'm convinced he wants to fight me. I want to fight him. If I'm not fighting Tyson Fury I'm not fighting at all."
His opponent, however, had a meltdown after the match. Joshua first hurled two of Usyk's belts to the canvas, left the ring and headed for the dressing room before turning around and stepping back into the arena to address the crowd in an expletive-laden speech.
"I just spoke from my heart. It has been so tough. You see AJ holding it together. I'm a hustler, so I try to keep things together, try work hard. Make sure my team is good," Joshua said in the presence of Saudi Arabia's Crown Prince Mohammed bin Salman.
"It comes at a cost. It would never break me but it takes real strength and tonight there's a little crack in the armour."