FUTURE UFC Hall-of-Famer Demetrious John will take on Muay Thai phenom Rodtang Jitmuangnon, in a modified MMA match-up.
Rodtang and Mighty Mouse will be battling it out at a special ONE Championship event that takes place on December 5.
Demetrious Johnson will return to action at ONE X December 5,
The contest will have a unique format that allows both men to show their skills.
The main event of the ONE X event, the four-rounder, will be played in alternating four- and three-minute rounds.
The Muay Thai rules will govern the first round, while the rules for the second round are mixed martial arts.
If the fight goes on for too long, the third round will see the contest go back under Muay Thai rules. The fourth and final stanza will see the contest go back to MMA.
Chatri Sityodtong, ONE Championship boss, announced the special rules bout on The MMA Hour earlier in this week.
He said to Ariel Helwani, "Basically, they both agreed right away.
"I believe they both thought about it for several hours, but both replied the exact same day."
Chatri enjoys the match-up and says: "It is so fascinating.
"Rodtang has only three minutes to knock out DJ. But if DJ survives, there is a lot on him. Rodtang must then survive three minutes worth of DJ's explosive wrestling or submissions.
"DJ is likely not going to strike with him."
He said, "It's going to be this kinda PRIDE-style fight back-to-the old-days."
"We wanted something special, something funny that would celebrate martial arts in a manner that celebrates all of MMA's history and not just our 10-year-old history.
"We have never done this crossover stuff. It's just like the old days of Asian MMA.
"It's going to be our largest and most unique show in our company's history."
"It's going to be crazy fun for fans around the world."
Johnson, who is widely considered to be the greatest mixed-martial artist of all-time, has not been in the cage since losing Adriano Moraes' ONE flyweight title in April.
Rodtang has not fought since his victory over Danial Williams, New Zealand, at ONE on TNT 1, in April.
