In a dream match-up for Silva in the -57kg weight class, she overpowered Hungarian Hedvig Karakas, who beat her in London four years ago when she was disqualified for an illegal hold.
The Carioca Arena 2 was rocking as the crowd went into a frenzy, stomping their feet and chanting "Rafa" as Silva tossed Karakas onto the tatami for the match-winning waza-ari.
"We felt very excited, we were so happy because she was able to move on," said Eduardo Mecking, a 44-year-old engineer who cheered on Silva with his wife and two young boys.
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"We're hoping she wins the gold medal."

Brazil's Rafaela Silva (white) competes with Hungary's Hedvig Karakas

Image credit: AFP

Her next obstacle on the way to a medal - and possibly Brazil's first gold at their home Olympics - will be London silver medallist Corina Caprioriu of Romania later on Monday.
A medal for Silva would mark a fairytale rise to the Olympic podium from a childhood in Rio's notorious Cidade de Deus favela, made famous in the film "City of God."
Following early years of trouble that saw her getting into fights in the neighbourhood, Silva found some structure to her life through judo and went on to attend the Instituto Reacao, founded by Olympic bronze medallist Flavio Canto.
The women's -57kg was among the toughest judo categories at Rio, featuring all four medal winners from the London Games.
In a rematch of the semi-final four years ago, London gold medallist Kaori Matsumoto of Japan battled London bronze winner Automne Pavia deep into 'golden score' extra time, conquering her French opponent with a waza-ari throw at the 3:50 mark.
World champion Matsumoto, who is nicknamed 'the beast', will face Mongolia's Sumiya Dorjsuren in the other semi-final.
Pavia, whose country has yet to win a judo medal in Rio, will try for bronze through the repechage rounds.
London bronze medallist Marti Malloy of the United States suffered a shock early exit in the round of 16.
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