On December 4, 2004, Kaoklai was the youngest and the lightest fighter ever to compete in the 12th annual K-1 World GP Championships, held in Tokyo Dome, Japan. His opponent, American slugger Mighty Mo, the winner of Las Vegas GP, was the heaviest at . Kaoklai started the fight cautiously circling the American, tossing in hard low kicks. At the end of the first round Kaoklai landed a lightning-quick jumping right high kick which connected flush to the head of Mo sending him unconscious to the canvas. This KO win over MO would not only send Kaoklai to the semifinals but earn him the nickname "Giant Killer". His amazing run in K-1 Finals came to an end however against Musashi by a closely contested extra round unanimous decision.