Charles Oliveira choked out Justin Gaethje in the first round to ensure the lightweight title remains vacant.
Oliveira was stripped of his title on Friday after weighing in half a pound over the 155lb limit. The Brazilian was therefore unable to win the belt against Gaethje who was challenging for gold for the second time.
But the former champion survived an early scare to drop Gaethje before submitting the challenger with a rear-naked choke. Oliveira extended his winning record to 11 fights and will challenge for the vacant title in his next fight.
"There is something missing here. The champion has a name and it's Charles Oliveira," said the winner. "This is a message to the entire division; I am. a problem for the entire division. I am the enlighted, I am the champion, this is my title and it should be here.
"Dana White, I don't care [who I fight next], I'm not going to choose. Hey, Conor McGregor, are you going to come back or are you going to run away?"
Both men were dropped in the opening stages with Gaethje hell-bent on pushing a ferocious early pace. He looked to have the former champion in trouble and cut him over his left eye, but once Oliveira took the fight to the ground, he quickly locked in the choke.
"The work the team puts in has paid off," the winner added. "We always work on submissions and to see the legacy of submissions still going... the work really paid off. It just shows the champion has a name and it's Charles Oliveira. I went into the octagon to defend my title, I don't have to get it back.
"He's a guy who pushes forward and I push forward and I knew this was going to happen. I knew I was going to get hit and I knew I was going to get him. It all came down to who wanted it more. The champion is Charles Oliveira and that isn't going to change."
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Gaethje was also choked out by Khabib Nurmagomedov in his previous title challenge but rebounded by beating Michael Chandler in a brutal back-and-forth war last year.
In the co-main event, Carla Esparza became a two-time strawweight champion with a points win over Rose Namajunas. The five-round snoozefest was booed by the Arizona crowd but Esparza had her hand raised after two of the three judges gave her the nod.
Earlier, Michael Chandler produced a brutal knockout of Tony Ferguson to re-establish his lightweight title credentials. Chandler lost to both Oliveira and Gaethje last year but put himself back into contention with a stunning second-round front kick which left Ferguson out cold.
