Diogo Reis will make the first defense of his ONE Flyweight Submission Grappling World Championship against Bebeto Oliveira at ONE Fight Night 50 on Friday, December 18.
ONE Championship announced the all-Brazilian title match on November 5. The bout is scheduled for Lumpinee Stadium in Bangkok and will be part of the promotion's final U.S. primetime card of 2026.
ONE Championship announces Diogo Reis vs. Carlos “Bebeto” Oliveira at ONE Fight Night 50.
November 3, 2026
View ONE Championship's original announcement.
Reis Reaches His First Defense
Reis has won all three of his appearances under the ONE banner. He opened his run with a kimura finish of Shoya Ishiguro, then defeated Daiki Yonekura over 10 minutes to capture the flyweight submission grappling title.
The two-time ADCC world champion returned in May at bantamweight and defeated Yuki Takahashi. That performance kept his ONE record perfect while giving him experience outside the division he now leads.
December's assignment changes the pressure. Reis is no longer chasing an open title or testing himself in a different weight class. He enters as the champion responsible for setting the pace and defending the standard he established against Yonekura.
Oliveira Arrives With a Complete Résumé
Oliveira will make his ONE debut in a world title match. The 32-year-old challenger has won world championships in both gi and no-gi competition and owns victories over Edwin Ocasio, Paulo Miyao and Thalison Soares.
His guard gives the matchup its central tactical question. Reis is at his best when he can keep the action moving, connect passing attempts and turn transitions into attacks. Oliveira is comfortable slowing those exchanges, creating control from the bottom and using sweeps or submissions to reverse the pressure.
The winner may be the athlete who decides the rhythm before the match settles into the other man's preferred game.
A Rivalry With History
This will not be the first final shared by Reis and Oliveira.
At the 2021 Abu Dhabi Grand Slam in Miami, Reis defeated Oliveira 1-0 in the 62-kilogram final. JJM's event report described an active match that ended with Reis taking the championship.
Five years later, the setting and competitive framework are different. Reis has added two ADCC titles and a ONE championship to his record. Oliveira arrives with the opportunity to reverse that earlier result while winning a major title in his promotional debut.
ONE Fight Night 50 also includes Kade Ruotolo's lightweight MMA bout against former ONE champion Ok Rae Yoon. Together, the two matchups give the December card a strong jiu-jitsu foundation across submission grappling and mixed martial arts.
Complete event information is available on the official ONE Fight Night 50 page.