The competition even made superstars out of American Frank Shamrock and Brazil's Royce Gracie.
The beauty of MMA lies in the combination of different fighting styles, said Chilson.
He should know. In his match on Wednesday night, he faced Taiwan's Zhang Jingxong (who goes by the nickname "Lightning"), an expert in the Chinese self-defence art of sanda.
Unlike Zhang, Chilson's expertise lies in muay thai andBrazilian jiu-jitsu.
"Zhang is a tough competitor and a highly decorated fighter in sanda," Chilson said. "I have great faith and confidence in my coaches, though. They've done everything to prepare me for the fight.
"I will go out there to execute what they've taught."
No matter how the duel - tipped to be the biggest fight of his career so far - turns out, Chilson hopes to live up to his nickname "The Dragon".
"Ever since I was a kid, my mum would tell me that I have a dragon guardian spirit protecting me.
"Being so young then, I didn't think too much of what she said. But the mental image of a dragon grew stronger and stronger over the years. I realised that it has always maintained a presence in my life. I have statues and pictures of dragons in my house."
Chilson also has a unique ritual before he enters the ring each time. To keep himself calm, he does "light meditation".
He has been influenced by Japanese culture all his life, said Chilson, who graduated from Western Washington University with a degree in nutrition. But he added sheepishly that unfortunately, he speaks the language "very badly".
"I can get by when I'm travelling in Japan, but that's about it."