Eight years after competing in his Olympic debut, Brin qualified for his third Filipino squad, as a 31-year-old, in the men's light welterweight division (63.5 kg) at the 2004 Summer Olympics in Athens by receiving a berth and capturing the title over Uzbekistan's Dilshod Mahmudov from the Asian Championships in his hometown Puerto Princesa. Brin was also appointed by the Philippine Olympic Committee to carry the Philippine flag in the opening ceremony, as his teammate Christopher Camat (originally selected to take the privilege) decided to witness his action for the next day's bout. Unlike his two previous Games, Brin outclassed Sweden's Patrick Bogere in the opening round with a satisfactory 43–35 triumph, before losing out his next match to Thailand's Manus Boonjumnong in a decisive score of 15–29.