Sixth-ranked challenger Osamu Sato wrested the World Boxing Association (WBA) super-bantamweight title from Yoddamrong Singwangcha on Saturday, when the exhausted Thai champion crumpled to the canvas midway through the eighth round.
Sato floored Yoddamrong twice in the seventh round at Saitama Super Arena and then went toe-to-toe with the champion in the eighth until Yoddamrong took a left to the body from Sato that sent him crashing to defeat.
Panamanian referee Guillermo Pineda signaled the fight over 1 minute, 58 seconds into the eighth round.
The victory was sweet vindication for Sato who was held to a controversial draw in a World Boxing Council (WBC) super bantamweight title fight by Willie Jorrin of the United States in February.
Sato's record improved to 26 wins, including 15 by knockout, one loss and two draws. The hard-hitting Sato becomes the ninth world champion to be affiliated with the Kyoei Gym in Tokyo.
Sato, successful in his second shot at a world title, also becomes the third reigning world champion associated with a Japanese gym, joining WBA minimumweight champion Keitaro Hoshino and WBC super flyweight champion Masamori Tokuyama, a third-generation pro-Pyongyang Korean resident of Japan.
Yoddamrong, meanwhile, suffered his first loss after 27 wins, including 12 by knockout, and a draw.