ONE Fight Night 31

{{Infobox MMA event

|name=ONE Fight Night 31: Kongthoranee vs. Nong-O 2

|image=ONE Fight Night 31.jpg

|image_size=

|promotion=ONE Championship

|date={{start date|2025|05|03}}

|venue=Lumpinee Boxing Stadium

|city=Bangkok, Thailand

|previousevent= ONE Friday Fights 106: Panrit vs. Suksawat

|followingevent= ONE Friday Fights 107: Ortikov vs. Dedduanglek

}}

ONE Fight Night 31: Kongthoranee vs. Nong-O 2 was a combat sports event produced by ONE Championship that took place on May 3, 2025, at Lumpinee Boxing Stadium in Bangkok, Thailand.{{cite web |last1=Blackett |first1=Todd |title=Dante Leon To Challenge Tye Ruotolo For Title At ONE Fight Night 31 |url=https://jitsmagazine.com/dante-leon-to-challenge-tye-ruotolo-for-title-at-one-fight-night-31/ |website=Jits Magazine |access-date=2025-04-04}}{{cite web |date=2025-02-14 |title=Tye Ruotolo to defend welterweight crown against Dante Leon at ONE Fight Night 31 |url=https://www.bjpenn.com/mma-news/tye-ruotolo/tye-ruotolo-to-defend-welterweight-crown-against-dante-leon-at-one-fight-night-31/ |access-date=2025-04-04 |website={{!}} BJPenn.com |language=en}}

Background

A flyweight Muay Thai rematch between Kongthoranee Sor.Sommai and former ONE Bantamweight Muay Thai World Champion Nong-O Hama headlined the event.{{Cite web |date=2025-04-04 |title=Thai legend Nong-O to rematch Kongthoranee in main event of ONE Fight Night 31

|url=https://www.sportingnews.com/us/mma/news/thai-legend-nong-o-rematch-kongthoranee-main-event-one-fight-night-31/ed7407b1ecf570f61d0fe312 |access-date=2025-04-04 |website=Sporting News |language=en-US}} The pairing previously to met at ONE Fight Night 28 in February 2025, which Kongthoranee won by split decision.{{Cite web |date=2025-02-08 |title=ONE Fight Night 28 Results: Kongthoranee Stuns Nong-O, Yamakita Overwhelms Adiwang

|url=https://www.onefc.com/news/one-fight-night-28-results-kongthoranee-stuns-nong-o-yamakita-overwhelms-adiwang/ |access-date=2025-04-04 |website=ONE Championship – The Home Of Martial Arts |language=en-US}}

A ONE Welterweight Submission Grappling World Championship bout between current champion Tye Ruotolo and Dante Leon served as the co-main event. The pairing met for the first time in Liverpool, England in 2020, where Leon won by decision. Their second meeting took place at FloGrapping promotion in 2021, which Ruotolo won by guillotine choke.{{Cite web |date=2025-02-13 |title=Tye Ruotolo To Defend Submission Grappling World Title Against Dante Leon at ONE Fight Night 31

|url=https://www.onefc.com/news/tye-ruotolo-to-defend-submission-grappling-world-title-against-dante-leon-at-one-fight-night-31/

|access-date=2025-02-13 |website=ONE Championship – The Home Of Martial Arts |language=en-US}}

A lightweight Muay Thai bout between Liam Nolan and Nauzet Trujillo was scheduled for this event.{{Cite web |date=2025-04-15 |title=Liam Nolan comes out of retirment to rematch Nauzet Trujillo at ONE Fight Night 31

|url=https://www.lowkickmma.com/liam-nolan-retirement-nauzet-trujillo/ |access-date=2025-04-22 |website=www.lowkickmma.com |language=en-US}} However, Trujillo withdrew from the event due to injury and was replaced by promotional newcomer Abolfazl Alipourandi on a one-day notice.{{Cite web |date=2025-05-01 |title=ONE Championship: Liam Nolan's return from retirement sees late change of opponent

|url=https://www.scmp.com/sport/martial-arts/article/3308683/one-championship-liam-nolans-return-return-sees-late-change-opponent |access-date=2025-05-01 |website=South China Morning Post |language=en}}

At the weigh-ins, three fighters failed to hydration test and missed weight for their respective fights:{{Cite web |date=2025-05-02 |title=ONE Fight Night 31: Kongthoranee vs. Nong-O II Weigh-In Results and Video

|url=https://combatpress.com/2025/05/one-fight-night-31-kongthoranee-vs-nong-o-ii-weigh-in-results-and-video/ |access-date=2025-05-02 |website=Combat Press |language=en-US}}

Former ONE Welterweight World Champion Zebaztian Kadestam weighed in at 195.25 pounds, 10.25 pounds over the welterweight limit. As a results, the bout was cancelled as Kadestam did not have medical clearance to compete.{{Cite web |date=2025-05-02 |title=ONE Championship: Zebaztian Kadestam 'not cleared to compete' after weight miss, fight vs Isi Fitikefu scrapped

|url=https://www.bangkokpost.com/sports/3016270/one-championship-zebaztian-kadestam-not-cleared-to-compete-after-weight-miss-fight-vs-isi-fitikefu-scrapped |access-date=2025-05-02 |website=Bangkok Post |language=en}}

Lucas Gabriel weighed in at 175.25 pounds, 5.25 pounds over the lightweight limit and he was fined a percent of his purse, which went to The Ultimate Fighter: China welterweight winner Zhang Lipeng.
Ali Saldoev weighed in at 140.25 pounds, 5.25 pounds over the flyweight limit and he was fined a percent of his purse, which went to Jhordan Estupiñan.