Qais Ashfaq has become the fifth Team GB boxer to be eliminated from the Olympics in the preliminary rounds.
The 23-year-old, who won silver in last year's European Amateur Championships, was beaten on points by Chatchai Butdee in their bantamweight 56kg clash.
The Brit, who told Sports Mole prior to the Olympics that he was aiming for gold, had to respond after the judges put Butdee ahead in the first round.
However, a knockdown in the second round shook Ashfaq, and despite getting back to his feet, it ended up being a comfortable win for Butdee, who is ranked seventh in the world at this level.
Half of Team GB's boxers have now exited the Games.