PHOENIX -- Charles Oliveira isn't the official champion. But he's the champion.
Oliveira, under extremely difficult circumstances, submitted Justin Gaethje via rear-naked choke just 3:22 into the first round of their lightweight battle at UFC 274 inside Footprint Center.
Oliveira (33-8) was scheduled to defend his title against Gaethje (23-4) at UFC 274 but was stripped of the belt instead after missing weight by half a pound on Friday. It meant that going into Saturday's fight, only Gaethje could win the belt; if Oliveira won, it would remain vacant.
If that had an impact on Oliveira's mindset, it was only a positive one. The Brazilian fighter was ultra-aggressive from the opening bell. He staggered Gaethje, who is from Arizona, immediately with a right hand and threw kicks to the body. Gaethje responded in kind. He dropped Oliveira twice in the very short fight, once with a left hook and again with a right. Both times Gaethje stepped back and allowed Oliveira to get up.
Oliveira, 32, even pulled guard at one point, but Gaethje, 33, backed off. However, it was a right hand down the middle by Oliveira that dropped Gaethje again and was the beginning of the end. Oliveira followed him to the floor and set up a triangle then a rear-naked choke. Gaethje refused to tap and went unconscious.
It's unclear what will happen in the immediate aftermath. This situation has never happened in UFC history, a defending champion missing weight and losing the belt on the scale. UFC president Dana White told Oliveira immediately after the fight he is a No. 1 contender and not a champion, although the sport will certainly continue to see him as such.
Also during the fight, a young woman ran from the stands and leaped onto the stage a few seconds after Oliveira submitted Gaethje. She started to climb the side of the cage, but was immediately slammed to the concrete several feet below by a security guard.
After seeming dazed for a few seconds, she tried to run toward a tunnel but stopped and sat in a chair. Security immediately swarmed and took her away right before Gaethje left the arena floor.
The Associated Press contributed to this report.