Mudranov won the men's 60kg final with a golden score victory over Kazakhstan's Yeldos Smetov, putting Russia's reduced team on the medals table.
Beslan Mudranov won Russia's first gold medal at the Rio Games in judo on Saturday and fired a warning shot that his country had plenty more to prove.
Russian President Vladimir Putin is also the honorary President of the IJF and had travelled to London four years ago to support his country's fighters at the Olympics.
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While Russia are basking in their big confidence boost, hosts Brazil are reeling from the setback of failing to win a first gold medal on the first day of competition.
He said: "I am now starting to think about this and I am at the same time realising that it is the first medal. And once I did that, and the final was over, I'm just very proud to be able to start off the Rio 2016 Olympic Games in such a positive manner for my country".
And if some reports from the U.S. turn out to be accurate Thrasher's gold is one of an expected 45 for the Olympic powerhouse Americans.
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They've already taken more Americans captives - probably as insurance until they receive the balance of that $1.7 billion. We've got a number of Americans being held all around the world, and I meet with their families, and it is heartbreaking.
Mudranov came out on top against the Kazakh judoka, winning by Waza-ari with Sasae-tsurikomi-ashi after 44 seconds at the Carioca Arena.
The International Judo Federation (IJF) had been outspoken in backing Russian athletes' right to compete. Japan's Naohisa Takato and Diyorbek Urozboev of Uzbekistan took bronze. They include the 12-strong judo team.
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