Russian Musa Mogushkov lost in the men's 66-kilogram division and Japanese Misato Nakamura was beaten in the women's 52-kilogram category.
Mogushkov lost to first-time Olympian Azerbaijani Tarlan Karimov in overtime. Mogushkov's coach Vitalii Makarov, said Mogushkov failed to get a good start in the match and was never able to recover.
Toronto's Sasha Mehmedovic opened the day with a win before being knocked out by Japan's Masashi Ebinuma, the world champion–in-title.
"Obviously I'm upset that I lost," said Mehmedovic. "I never like to look at the match tableau and see who I'm up against prior to starting the competition, only this morning did I learn that I would face the world champion in the second round.
"Two years ago I fought him and the bout was a lot tighter than today's (Sunday)."
Misato Nakamura was beaten by North Korean An Kum Ae. Nakamura previously lost to An at the Beijing Olympics and had been hoping for revenge in London. She said she was "full of regret."