Kongchai Chanaidonmueang headlines ONE Friday Fights 140 this Friday, January 30, carrying 15 appearances on the weekly series and a burning desire to earn that coveted US$100,000 contract. But as the former Rajadamnern Stadium World Champion prepares for his strawweight Muay Thai rematch against Thway Lin Htet, he credits much of his success to someone who isn't here to see it – the legendary Lumpinee Stadium and Rajadamnern Stadium World Champion Sangtiennoi Sor Rungroj, the mentor who shaped not just his fighting style, but his entire approach to the sport and life.

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The Legend Who Built Champions

Kongchai is ready to kick off his 2026 campaign in a high-octane main event at Lumpinee Stadium, but his path to this moment was paved by the teachings of a true Muay Thai legend. Sangtiennoi wasn't just another coach – he was a World Champion who conquered Thailand's most prestigious stadiums and served as the main training partner of 10-time World Champion John Wayne Parr, earning respect throughout the global combat sports community.

In 2000, Sangtiennoi – also known affectionately as Kru Tu – opened Tor Sangtiennoi gym in Pathum Thani, just outside Bangkok, where he dedicated himself to training a new generation of fighters. Among those young athletes walking through his doors was a teenage Kongchai, hungry to learn from a master who had already achieved everything in the sport. The lessons that followed would shape the fighter Kongchai would become.

Sangtiennoi's teaching philosophy centered on authenticity – the belief that what you do in training becomes who you are in the ring. No shortcuts, no half measures, and no going through the motions. Every strike thrown in the gym mattered, every round of pad work counted, and every moment of training shaped the fighter who would eventually step onto the biggest stages.

"The one thing that sticks with me is how he always told me to strike with speed and power. He said if you're lazy or half-hearted during training, you'll be the same way once you're in the ring. You can't just go through the motions," Kongchai explained. "Some fighters slack off when they don't have a fight scheduled and only start pushing two weeks before the event. You have to acknowledge what you should and shouldn’t do. The right thing is you have to strike with heart. Whatever you do in the gym is exactly what's going to show up on fight night. It becomes a part of you. That's what he taught us.”

Lessons Beyond The Ring

But Sangtiennoi understood that building successful fighters required more than perfecting technique and conditioning. He educated his athletes about work ethic, financial responsibility, and planning for life beyond the ring. The legend had watched too many fighters achieve success only to end up broke years later, and he refused to let that happen to the young men training under his guidance.

Sangtiennoi took an active role in managing his fighters' finances, helping them open bank accounts and teaching them the importance of saving versus spending. His approach went beyond coaching – he acted as a mentor, father figure, and financial advisor, holding onto his fighters' bankbooks to ensure they weren't squandering their earnings on impulse purchases that would leave them with nothing when their careers ended.

"He taught us a lot about discipline, especially with money. As a fighter, you get a big lump sum after a win, and if you're not careful, it's gone in a flash," Kongchai continued. "He made us all open bank accounts. Every time I got paid, I'd send some [money] to my mom, save some, and keep a bit for spending. He even held onto our bankbooks for us. He always said your savings should be bigger than your spending. He truly wanted the best for us.”

Fulfilling A Dream

Though Sangtiennoi passed away in 2021, his vision for his fighters extended beyond Thailand’s world-famous stadium circuit.

The icon was a big fan of ONE Championship and how the organization conducted its events – particularly regarding the absence of gambling, which had plagued traditional Muay Thai for decades. In the country's stadium scene, bookies set odds and pressured fighters to perform specific ways, creating an environment where the sport's integrity was compromised at times.

Sangtiennoi saw ONE as the future of Muay Thai – a platform where fighters competed based purely on skill, training, and their own style without outside pressure from gambling interests. He desperately wanted Kongchai and his other fighters to reach ONE’s global stage, where the sport's purity could shine without the corruption that had tainted so many traditional bouts.

Now making his 16th ONE Friday Fights appearance, Kongchai carries his mentor's dream into every fight. Each time he steps into the ring at Lumpinee Stadium under the ONE banner, he's honoring the vision Sangtiennoi had for his fighters – competing in an environment where only skill matters and where the sport's integrity remains intact.

"He really wanted the fighters in our gym to compete in ONE because ONE has no gambling concerns. He hated the gambling in traditional Muay Thai settings. The way the bookie set the odds and put so much pressure on the fighters, sometimes you're forced to fight a certain way just because the bookie says so. And if you don't, you get trashed for it," Kongchai recalled.

"Kru Tu always said that in ONE, it's all about the rules and the sport, not the gambling. You fight based on your skill, your training, and your own style. There's no outside pressure. Now that I'm finally fighting in ONE, I'm proud of myself for fulfilling his dream. My only regret is that he's not here to see it. If he were still with us, I know he'd be so proud, and that would mean the world to me."

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