Japan's Saori Yoshida won a third successive Olympic gold in the women's 55kg freestyle wrestling.
Nine times world champion Yoshida faced Canadian Tonya Lynn Verbeek in a repeat of the final at the Athens Games.
Verbeek again had no answer to Yoshida's dominance and expertise and was comfortably beaten.
Colombian Jackeline Renteria Castillo took one bronze, while Azerbaijan's Yuliya Ratkevich came through the repechage before winning the other.
Yoshida's victory provided Japan with three gold medals in the four women's categories.
Great Britain's first Olympic wrestler Olga Butkevych lost in agonising fashion in the first round to Lissette Alexandra Antes Castillo.
Butkevych, who came to Britain in 2007 and gained citizenship in May, lost after her 21-year-old opponent pushed her off the mat with just four seconds of the final round left.
"I'm sorry, I'm sorry," a tearful Butkevych said afterwards. "It's my big competition, once every four years. I've been competing every year for the past four years.
"But this year, the big year, I lost. I didn't feel pressure from the crowd, but I was proud to be there for them.
"There were so many people here to support me and I'm proud but sorry."