Thai slugger Jaosuayai Mor Krungthepthonburi knows exactly what he's up against at ONE Friday Fights 137, and he couldn't be more excited about the challenge.The flyweight Muay Thai standout makes his strawweight debut in ONE Championship on the organization's final event of 2025, which emanates live from the iconic Lumpinee Stadium in Bangkok, Thailand, this Friday, December 19.He takes on former two-division, two-sport ONE world champion Sam-A Gaiyanghadao, an opponent the Sor Dechapan warrior revealed he has deep respect for."I see Sam-A as a true Muay Thai legend with no flaws, whether it's his strategy, striking, heavy left kick, or toughness. I consider this the toughest opponent of my career," Jaosuayai told ONE Championship in an interview.That honest assessment shows how seriously he's taking this strawweight debut.Jaosuayai built his reputation in the flyweight division, where six of his eight promotional victories came via knockout.His devastating power overwhelmed opponents like Denis Puric, Nakrob Fairtex, and Yodlekpet Or Atchariya during a five-fight winning streak that established him among the division's most dangerous finishers.But Sam-A operates at a completely different level.The former champion's decorated career spans multiple weight classes and combat sports disciplines. He's built the kind of well-rounded excellence that's made him arguably one of the greatest fighters today across more than 400 bouts.As such, fight fans should be in for a treat when these two striking titans collide at ONE Friday Fights 137, which will be available live in Asia primetime this Friday on ONE Championship's official YouTube channel, the ONE Super App, and watch.onefc.com. Geo-restrictions may apply. View this post on Instagram Instagram PostJaosuayai says he's bringing an even better package at strawweightBefore building a reputation as one of the flyweight Muay Thai division's most dangerous finishers under the ONE spotlight, Jaosuayai primarily competed in the strawweight division for years.Understandably, this move back to his usual weight class has got the 24-year-old Sor Dechapan product feeling at the peak of his powers before he trades leather with the martial arts icon inside the Mecca of Muay Thai."I feel more energetic, elusive, and faster now, which should lead to more evenly matched and exciting opponents than at 135 pounds. However, I want to emphasize that I am happy to fight at both 125 pounds and 135 pounds," he told the promotion in the same interview.Will he get his hand raised, or will the legendary Sam-A attain another memorable victory come fight night on December 19?