From information I have researched, this is what I have been able to come up with...
In September 1983 Don Wilson gave Thai Champion Pongdejoi Prasobchai a beating, knocking him out in Hong Kong. The Thai's refused to believe this loss was legitimate and the Thai’s wanted Wilson to come to Bangkok to fight Champion Samart Prasanmitr. Wilson took the lucrative fight on the understanding that he was going to fight in Samart's backyard and the only way he could probably win was by KO. Wilson was paid $1,000,000 Hong Kong dollars ($122,000 American). Samart was guaranteed $10,000 Hong Kong dollars. It is rumored the Thai would have been paid as much as $200,000 Hong Kong if he knocked the American out. The purse got so high during the negotiations of the rules for the fight. Each time the Thai's wanted a Muay Thai rules, Wilson would say no and the Thai’s would pay money to have the rules included in the match. The 2 athletes had a considerable weight difference with Wilson at 172 lbs. while Samart weighed 148 lbs. Wilson was told that his weight would make no difference as far as the Thai fighter and the fans were concerned so the American approached the fight like he was preparing for a fight against another 175 lbs. athlete. Things changed at the weigh in and the Thai officials harassed Wilson about his weight and they wanted him to lose weight. Wilson sat in a sauna on the day of the bout. Wilson felt there were other methods used to try and demoralize him including: a small dressing room infested with mosquitos, armed guards, military personnel assigned to guard the 3 garbage bags full of money wagered on the outcome of the fight. "It made me concerned to see those guns and all that money in my dressing room," said Wilson. The five round bout of three minutes per round went the following way:
Wilson won the first round handily but at the end of the round a Thai came over and said, "Not good. You lost that round pretty badly." Wilson won the round with sidekicks to the body and punches to the head. Wilson was told that groin techniques were not allowed in the rules but he claims he was continually attacked in the groin from the start of the first round. Wilsons brother was baffled why Wilson had trained so hard to deliver sidekicks to the legs but did not use them during the fight. Wilson has stated he did not use them because the Thai was so easy to hit with the fist that he decided he would keep using these weapons until the Thai went down. The videotape of the bout was confiscated by the Thai military after the bout so this result is the recollections of the Americans who watched the bout. The second round was again Wilson's though by a smaller margin. Surprisingly, the Thai who told Wilson he lost the first round showed up and stated that Wilson could only win the fight now by KO. Wilson changed his strategy and started to press more for the KO. The 2 athletes had established what they were capable of now with Wilson using the sidekicks and the punches whereas Samart would press with knees and elbows. In the middle of the 3rd round, Wilson was caught with a knee to the back of the spine. The Thai was considered the winner in this round even by the Wilson's. The 4th round was even worse for Wilson. From the knee to the spine Wilson complained he could not get control of his muscles. During this round he was dropped twice with knees to the body. Wilson took the counts but managed to last until the end of the round. In the rest period for the final round, Wilson said he had recovered and he was standing for the final opening bell. When it sounded he met the Thai with a flurry of of punches that had Samart bleeding from the nose and mouth. Wilson was the aggressor now but the Thai had built up a commanding lead by winning 2 rounds clearly as well as Wilson suffering several knockdowns. Neither fighter could have went another round and this did not matter because Samart won the match handing Wilson his 4th loss in his entire career. Samart was not happy with the win and he was jeered by the Thai's because he could not fight back. Wilson unhappy with his loss went over to congratulate the Thai, but Samart would not shake his hand. Up to this point the story is that the fight attracted the largest fight crowd ever to Lumphini Stadium. It was the largest amount of money ever bet on a fight there as well. Wilson spent $10,000 to buy himself a Presidential Rolex in Hong Kong on his way back to America. Years later Wilson claims that the bout was rigged. He claims Thai officials made him lose 8 lbs. before the bout took place. And he also claims that the Thai's reduced the number of rounds without letting him know.