There are upsets in sports, and then there are upsets that make you question everything you thought you understood about how competitive dynamics work. Julianna Pena stopping Amanda Nunes at UFC 269 in December 2021 was the second kind.
Nunes was not just a favorite going into that fight. She was, at that point, arguably the most dominant champion in UFC history across any gender or weight class. She had not lost in five years. She had beaten everyone. She was coming off a somewhat less active period but there was no serious case to be made that Pena, a tough fighter who had been inconsistent in her UFC career up to that point, was going to beat her.
And then the second round happened.
Pena had survived the first round, which was notable on its own, because Nunes often finished opponents before they got a chance to settle in. She was aggressive. She was going forward in a way that Amanda was not immediately solving with movement or counters. When they hit the mat in the second round and Pena got her back, you could feel the shift in the building. Amanda was tired. Pena was relentless. The rear naked choke finished it.
The reaction was enormous. Amanda Nunes had been submitted. The "Lion Queen" had been dethroned by a challenger who most people had not given serious odds. It was one of those fights that you remember where you were when you watched it.
Let's give Julianna Pena her full credit here, because she does not always get it. She fought a smart fight. She was in excellent condition. She did not panic when Nunes pressured her. She recognized that Nunes was fading and she pushed the pace specifically to exploit that. The choke finish was clean. She won that fight, and the upset was not a fluke in the sense of random chance going her way. It was a game plan that worked.
What came next was the build to the rematch, and the rematch is where the narrative got complicated.
UFC 277 in July 2022 was the Pena-Nunes rematch, and it was not close. Nunes came back with different conditioning, a different approach, and a ferocity that had not been present in the first fight. She dominated five rounds. She landed punches and kicks at will. Pena showed heart and never stopped coming forward, but there was no real question about the winner after the first two rounds. Amanda won by unanimous decision and reclaimed the belt.
What does the rivalry mean? A few things worth thinking through.
First, it exposed something real about Amanda Nunes at a specific point in her career. The first Pena fight happened at a moment when Nunes was perhaps not at her sharpest. She had been less active, the training camp had questions around it, and the physical intensity that had made her so terrifying was not fully present. The second fight showed what Nunes at her best looked like against the same opponent: comprehensive domination.
Second, it gave Julianna Pena a legacy that she did not have before. Whatever else happens in her career, she will always be the person who submitted Amanda Nunes. That is genuinely rare and genuinely significant. The belt she held was real. The defense she made against Nunes in the rematch was not enough to keep it, but she is now in a different category as a fighter than she was before December 2021.
Third, it raised questions about how much of Amanda's dominance was based on a level of physical conditioning and mental sharpness that was vulnerable to disruption. The best fighters are always vulnerable to the right person at the right moment. The Nunes mythology absorbed a lot of assumptions about her invincibility that the Pena fight punctured.
Nunes eventually vacated both titles in 2023, at which point her career was winding down. The bantamweight title picture opened up, and the division began reshaping itself. Pena has remained a significant figure in the division, fighting for the title again and continuing to be involved in the top of the rankings.
The full story of this rivalry is not just a story about two fighters. It is a story about how even the greatest fighters have moments of vulnerability, about how preparation and game planning can overcome talent gaps, and about how the sport's unpredictability is one of its greatest qualities.
If you want to understand women's bantamweight MMA, the two Pena-Nunes fights are essential viewing. They tell you a lot about what is possible when a determined challenger meets a champion at a specific moment.
UFC Fight Pass has both fights available. Watching them back-to-back is one of the more interesting experiences in recent women's MMA -- two completely different stories in two fights.
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