Julianna Pena stunned the mixed martial arts world by defeating Amanda Nunes via submission at UFC 269. She sunk in a rear-naked choke in the second round to win the belt and dethrone 'The Lioness'.Pena engaged in a stand-up barnburner with Nunes as both the bantamweight fighters repeatedly landed heavy strikes.'The Venezuelan Vixen' defeated the long-reigning champion and claimed gold in stunning fashion inside the T-Mobile Arena, leaving those in attendance and fans worldwide in utter disbelief.UFC welterweight champion Kamaru Usman, bantamweight titleholder Aljamain Sterling, former two-division champ Daniel Cormier and Bellator women's featherweight champion Cris Cyborg were the first to react to the spectacular UFC 269 co-main event result.Check out their tweets below:KAMARU USMAN@USMAN84kgWooooooooooow!!! What did I just watch?? Peñaaaaaaaa!!! #UFC26910:31 AM · Dec 12, 2021113831599Wooooooooooow!!! What did I just watch?? Peñaaaaaaaa!!! #UFC269Jamahal Hill@JamahalHHoly shit!!! Never count everybody out!!!#AndNew #UFC26910:32 AM · Dec 12, 202123513Holy shit!!! Never count everybody out!!!#AndNew #UFC269Aljamain Sterling@funkmasterMMAANYTHING IS POSSIBLE!! NEVER FORGET THAT!! #UFC269!10:34 AM · Dec 12, 20213402380ANYTHING IS POSSIBLE!! NEVER FORGET THAT!! #UFC269!Daniel Cormier@dc_mmaAbsolutely amazing ! Congrats to the Venezuelan vixen!!!!! That’s why they play the game ! #ufc 269 @venezuelanvixen10:37 AM · Dec 12, 20213524277Absolutely amazing ! Congrats to the Venezuelan vixen!!!!! That’s why they play the game ! #ufc 269 @venezuelanvixenShayna Baszler@QoSBaszlerShe didn’t just beat Nunes. She didn’t even have hooks in. She broke Nunes. We live in bizzaro world, now. #UFC26910:36 AM · Dec 12, 20214173582She didn’t just beat Nunes. She didn’t even have hooks in. She broke Nunes. We live in bizzaro world, now. #UFC269@CrisCyborg.com@criscyborg🙏🏽 congrats @VenezuelanVixen #CyborgVsNunes210:38 AM · Dec 12, 202158185🙏🏽 congrats @VenezuelanVixen #CyborgVsNunes2 https://t.co/AXI1DOY7ZQDerek Brunson@DerekBrunsonImagine having a 8-15 legs parlay and losing a lock like Nunes / Peña , lol . I’d be sick 😂😂😂10:40 AM · Dec 12, 202132116Imagine having a 8-15 legs parlay and losing a lock like Nunes / Peña , lol . I’d be sick 😂😂😂Tony Ferguson@TonyFergusonXTGreat Fight @VenezuelanVixen # Jab🥇Central 🥊💨🍃 Well Earned -CSO- 🇺🇸🏆🇲🇽10:41 AM · Dec 12, 2021140567Great Fight @VenezuelanVixen # Jab🥇Central 🥊💨🍃 Well Earned -CSO- 🇺🇸🏆🇲🇽Henry Cejudo@HenryCejudoNunes didn’t use her power correctly. Got to emotional, taped due to exhaustion.(no legs in choke) Peña was right Will won this fight. Congrats Juliana Pena #ufc26910:44 AM · Dec 12, 202195859Nunes didn’t use her power correctly. Got to emotional, taped due to exhaustion.(no legs in choke) Peña was right Will won this fight. Congrats Juliana Pena #ufc269#OnAmission4Gold@KelvinGastelumI remember riding bus back 2my hotel after winning TUF! A girl ran up 2me,congratulated me and said 1 day im going to win that show.I thanked her and didn’t think much of it. Ppl always say that kinda stuff. So I thought. Congrats @VenezuelanVixen on making ur dreams come true.10:47 AM · Dec 12, 202121915I remember riding bus back 2my hotel after winning TUF! A girl ran up 2me,congratulated me and said 1 day im going to win that show.I thanked her and didn’t think much of it. Ppl always say that kinda stuff. So I thought. Congrats @VenezuelanVixen on making ur dreams come true.Amanda Nunes will most likely get an immediate rematch with Julianna Pena considering her achievements inside the octagon over the last few years. The Brazilian was riding a 12-fight winning streak going into the bout, with her last defeat coming in 2014.Amanda Nunes' 12-fight winning streak in the UFC has come to an endAmanda Nunes is considered the greatest female mixed martial artist of all time. Nunes won the UFC women's bantamweight and featherweight titles, and unlike the other double-champions in the sport, she has been defending both belts. Julianna Pena became the first fighter to defeat Nunes since Cat Zingano at UFC 178 in September 2014. The 33-year-old superstar was on a dominant 12-bout winning streak going into her title fight at UFC 269.Hence, Pena's win over Nunes has to be considered as one of the greatest underdog triumphs in the sport. The new champ started the bout as a +600 underdog.