Australian light-heavyweight Damien Hooper has received a warning from Olympic officials for wearing a T-shirt featuring an Aboriginal flag.
Hooper, who dispatched Marcus Browne of the United States, broke the rule that forbids athletes to use the Games as a political platform.
However, the 20-year argued that he was proud of his cultural heritage.
"I'm not saying that I don't care, I'm just saying I'm very proud of what I did," said Hooper.
Hooper now faces Russia's Egor Mekhontcev in the last 16.