Russia's Roman Vlasov and Hamid Soryan Reihanpour of Iran won Olympic gold medals on the opening day of the Greco-Roman wrestling on Sunday.
World champion Vlasov, 21, won the under-74kg division while five-time world champion Reihanpour took under-55kg gold.
Vlasov beat Arsen Julfalakyan in the final by two rounds to none, denying the Armenian the chance to emulate his father Levon's title for the Soviet Union in Seoul in 1988.
"I feel great, I still can't quite believe it but I'm sure I will soon," said Vlasov.
"It's wonderful, I'm very happy but also very grateful to everyone who has been supporting me. I want to congratulate Arsen who has been my opponent for many years and whose father was Olympic champion.
"Every time we fight it's difficult."
Julfalakyan said he would have liked to make history for his family links but his main aim was the gold medal for himself.
"I'm proud of my whole family, it's great to have such a legacy but when you travel to the Olympics and look forward to your competition, you think only about yourself, your progress, your possible rewards and your hope for gold.
"If I'd won the gold medal then there would have been an entry in the record books for another Olympic champion in the same famly.
"It hasn't happened this time but my career's not over and I'll do all I can to make it happen next time."
Aleksandr Kazakevic of Lithuania and Emin Ahmadov of Azerbaijan won the two bronze medals.
Soryan Reihanpour made up for his disappointment in Beijing four years ago, when he finished fifth, by beating Azerbaijan's Rovshan Bayramov for the under-55kg title.
The 26-year-old Iranian won world titles in 2005, 2006, 2007, 2009 and 2010, but was only fifth in the Beijing where he had been favourite.
"I hope that I have made everyone happy back home. Beijing was a bitter experience for me but I used that experience to achieve this victory today," he said.
Peter Modos of Hungary and Mingiyan Semenov of Russia took the bronze medals.