A historic world title match will headline ONE Fight Night 17 on Dec 9.
Two-division ONE kickboxing world champion Roman Kryklia will welcome WBC Muay Thai heavyweight world champion Alex Roberts to ONE Championship.
On that day, the inaugural ONE heavyweight Muay Thai world title will be on the line.
The heavyweight blockbuster will serve as the main event of ONE's first all-Muay Thai card to air live in US primetime from the Lumpinee Boxing Stadium in Bangkok.
Kryklia has left a trail of destruction through the heavier kickboxing divisions on his way to claiming the ONE light heavyweight kickboxing world title.
The towering Ukrainian is unbeaten in his five appearances since making his promotional debut back in 2019, and four of those victories have come inside the distance.
His most recent win was an epic comeback over Iraj Azizpour at ONE 163, where he rose from the canvas to stop the Iranian knockout artist in the second round and win the ONE heavyweight kickboxing world grand prix championship.
The 32-year-old has an impressive 49-7 professional record. Most of those fights have come in kickboxing, but Kryklia is no stranger to "the art of eight limbs," having trained and competed under Muay Thai rules earlier in his career.
Fighting out of Thaiboxing Pit, on the other hand, is Roberts. He comes to the ONE ring hot on the heels of his WBC world title victory back in his home city of Perth, Australia, last month.
"The Viking" overcame the UK's Lyndon Knowles -- one of two-sport ONE bantamweight world champion Jonathan Haggerty's coaches -- to claim the belt by unanimous decision.
It was the crowning achievement of the 34-year-old's combat sports journey so far, but he now faces the biggest fight of his career when he meets one of the most dominant strikers in the world for the historic inaugural heavyweight Muay Thai strap.
The announced bouts at ONE Fight Night 17 include: inaugural ONE heavyweight Muay Thai world title: Roman Kryklia v Alex Roberts; featherweight Muay Thai: Jo Nattawut v Luke Lessei; bantamweight Muay Thai: Felipe Lobo v Saemapetch Fairtex; flyweight Muay Thai: Edgar Tabares v Johan Ghazali; flyweight Muay Thai: Nguyen Tran Duy Nhat v Denis Puric; and catchweight (120lb) Muay Thai: Thongpoon PK Saenchai v Ellis Barboza.