Thai boxers Jomthong Chuwatana and Kwanthai Sithmorseng were stopped in their title fights in Tokyo yesterday.
In the WBA super-featherweight championship, Jomthong suffered the first loss of his career when he was knocked out by champion Takashi Uchiyama in the second round at Ota Ward Gymnasium.
The 25-year-old Thai had won all his nine fights but the Japanese proved much too strong for the seventh-ranked challenger.
The 35-year-old Uchiyama registered his 19th knockout in 23 wins and one draw.
He successfully defended the title for the 11th time after winning it from Mexican Juan Carlos Salgado in 2010.
In the light-flyweight division at the same venue, Kwanthai was stopped by champion Royoichi Taguchi in the eighth round.
It was the Thai's fourth loss against 49 wins (26KOs) and one draw, while the 28-year-old Japanese registered his ninth knockout in 22 wins against two losses and one draw.
It was the first defence of the title for the Japanese who won the belt by beating Alberto Rossel of Peru on points in December.
Kwanthai was also stopped by then-champion Kazuto Ioka in his attempt for the title in 2013.
He was crowned WBA minimumweight champion in 2010 with a split decision over compatriot Pigmy Kokietgym.
He then lost the title to Muhammad Rachman in his first defence in Indonesia recently.
Meanwhile, former professional boxer Andrew Lewis has died in his native Guyana after a motorist struck him on his bicycle. He was 44.
Police in the South American country say Lewis was struck Monday on a major road outside the capital.
The retired boxer, nicknamed "Six Heads," was pronounced dead at a hospital.
Lewis became the first boxer from Guyana to earn a world title. In 2001, he beat American James Page to win the WBA welterweight crown in Las Vegas.