A historic battle headlines ONE Fight Night 17 this weekend when ONE light heavyweight kickboxing world champion Roman Kryklia takes on Australia's Alex Roberts for the inaugural ONE heavyweight Muay Thai world title.
Indisputably, it's the largest Muay Thai fight in ONE's history, and it takes place at the iconic Lumpinee Boxing Stadium in Bangkok tomorrow.
Here, we look at what each man brings to the tussle and what they could use to emerge as ONE's very first heavyweight Muay Thai king.
Kryklia's knees
Kryklia's knees have been a deadly weapon so far in his unbeaten five-fight run under the ONE banner.
Using his height, the towering Ukrainian is able to land to his opponents' faces with his knees from punching range, making him exceptionally dangerous during exchanges.
The shackles will be released further under Muay Thai rules, which will allow the 32-year-old Ukrainian to control Roberts in the clinch and unload knees without fear of the referee breaking up proceedings.
Roberts' clinch
Roberts might be even more dangerous in the clinch.
"The Viking" is a 10-year Muay Thai veteran and has dedicated his entire career to the sport, unlike Kryklia who has largely campaigned in kickboxing after a transition from "the art of eight limbs" earlier in his life.
As a genuine specialist, Roberts could hold the advantage once the fight enters the clinch, and his skills could see him manhandle Kryklia and land knees of his own.
Such dominance would allow him to wear the light heavyweight kickboxing king down and punish him over the course of the five-round world title battle.
Ukrainian's punches
Despite his size, a feature of Kryklia's game is his hand speed.
Using his speed and 82-inch reach, the ONE heavyweight kickboxing world grand prix champion will be able to use his straight punches to dictate terms against Roberts.
The long punches have been another effective weapon for Kryklia in his career, leading him to 27 knockout wins over bamboozled opponents during his career.
If he can use his length to keep Roberts at bay, it could be a long night for the Aussie who will need to solve the range puzzle, close the distance, and land shots of his own.
Aussie's weapons
Which brings us to another of Roberts' biggest weapons heading into ONE Fight Night 17 -- close range attacks.
The 34-year-old showed in his recent WBC Muay Thai heavyweight world title win that he can throw down at close quarters, and he'll need to repeat the dose if he is to take down Kryklia and upgrade his status to the heavyweight Muay Thai king.
If he can stay close to Kryklia, Roberts will be able to throw heavy punches while his taller foe is cramped for room. In 4-ounce gloves, it might only take one to close the show.
Similarly, the Perth native will be able to use his elbows -- another advantage of his Muay Thai background -- to do damage when the heavyweight pair tie up.