Julianna Pena officially etched her name in the UFC history books with a stunning second-round submission upset win over Amanda Nunes to win the women's bantamweight title in the co-main event of UFC 269 from Las Vegas. 

After getting the better of the champion with her jab in the second round she took down the champ and sank in a rear-naked choke that earned her the belt. 

The fight started with a pretty grappling-heavy flavor. While the ground game was potentially Pena's best chance to win on paper, it was a strong round for the Lioness. She maintained dominant position throughout the round and successfully defended Pena's Kimura attempt at the end of the round. 

The next round didn't go so well for the now-former champion. Pena's upset bid was officially in business from the sounding of the second bell. She got in Nunes' face and refused to relent.

Pena utilized a pesky jab to keep the pressure on the Lioness as the two got into a slugfest. That kind of fight favored Pena, and it looked like she may score a knockout victory. 

Instead, she opted for a takedown and quickly went to work on a rear-naked choke. Seconds later, Nunes was tapping and the division got a new champion for the first time since 2016. 

The Venezuelan Vixen has been calling for a fight against Nunes for quite some time. As it turns out, that confidence carried her in a big way come fight night. 

This is among the most shocking upsets in UFC title fight history. For context, Holly Holm was +850 (bet $100 to win $850) when she pulled off her upset win over Ronda Rousey. DraftKings Sportsbook had Pena's odds against Nunes at +650. 

Pena as the champion opens the doors for lots of former challengers who had been shut out by Nunes, but the first order of business is likely to be an immediate rematch. That's the standard operating procedure for a champion of her caliber. 

The new champ already addressed it before her UFC 269 win. 

"Yes, (there will be) an immediate rematch," Pena told the media on Thursday. "And when I win that fight, I will be 11-2 in the division, which is a better bantamweight record in the history of the bantamweight division. As far as walking up to 145 (for a second belt), I don't know, I'm pretty comfortable in knowing that 135 is my proper weight class. But we can cross that bridge when we get there." 

With Pena now proving her fire for this fight was enough to score the win, that's a fight that would carry a lot of intrigue for fans. 

Now that Pena is the champ, she can put an exclamation point on the rivalry with a second win.