Russian Arsen Galstyan earned gold in the men's 60kg event on Saturday, while Sarah Menezes of Brazil captured judo gold in the women's 48kg.
After besting favorite Rishod Sobirov in the semifinals, Galstyan earned the top medal in his Olympic debut with a win over Japan's Hiroaki Hiraoka. The 23-year-old had won a world cup in Spain earlier this year and needed just 41 seconds to score an ippon.
"I can't believe it yet that I won," said Galstyan. "I was determined to go for the gold. My dream was to become an Olympic champion."
Hiraoka's silver gave Japan its seventh all-time medal in this event, leading all countries.
Sobirov failed to become the first Uzbek judoka to win an Olympic gold, but the reigning world champion did pick up a bronze medal for a second straight Olympics. Also grabbing bronze in the event was Brazil's Felipe Kitadai.
Menezes, a former bronze medal winner in the world championships, bested 2008 Beijing gold medal winner Alina Dumitru of Romania to capture her first Olympic medal.
With the win, Menezes captured Brazil's first gold medal in a woman's judo event and first in the sport since a gold in the men's 66kg at the 1992 Games.
"I'm loving this moment. It's the first time a Brazilian woman has won an Olympic gold medal (in judo)," noted Menezes. "I had to control my anxiety and tiredness but I'm so happy. The women of Brazil have fought so hard to get a medal."
Dumitru came in as the favorite thanks to her Beijing medal as well as three world medals. The 29-year-old had announced at the recent European Championships that she plans to retire following the London Games and is staying true to her word.
"This is my last Olympic Games. I want to go and have a family," she said.
The bronze medals in the women's 48kg matches went to Belgium's Charline van Snick and Eva Csernoviczki of Hungary. The 21-year-old van Snick topped 2008 bronze medal winner Paula Pareto of Argentina, while Csernoviczki captured her country's first medal of any kind since 1992.