The 21-year-old trailed Georgia's three-time world champion Geno Petriashvili until the dying embers of the 125 kilograms freestyle bout, but managed to strike when it mattered most.

Steveson forced Petriashvili to the mat for a takedown and although it was challenged by the Georgian's corner, the judges ruled that it was a valid move.

He won the bout 10-8 with his last-gasp effort earning him a cool $250,000 (£180,000/€212,000) which USA Wrestling pays to all Olympic gold medallists.

As well as beating Petriashvili, who has won the last three world titles in a row, Steveson also knocked out Turkey's reigning Olympic champion Taha Akgül in the quarter-finals.

"I knew I had it in me," said Steveson, who is tipped to be a star with World Wrestling Entertainment (WWE).

"The reason I was stunned was because the US has not had a heavyweight champion in 20 plus years, and I did it at 21 years old.

"I'm not sure what I'm gonna do with a quarter million dollars, put some of it away?

"I try to be smart with money.

"I'll probably go take my family out to eat, we all got to eat steaks back at home, probably buy my mom a Louis Vuitton purse, she deserves it.

"She's back at home breaking a sweat watching me wrestle, so she deserves something nice.

"I'm gonna do good things with it, hold it, and I'm just gonna live my life the way I've been living it."

Bronze medals in the division were won by Akgül and Iran's Amir Hossein Zare.

There was another dramatic final in the women's 53kg division as Japan's home wrestler Mayu Mukaida pulled off a great escape from 4-0 down to win gold.

Mukaida, who has won the World Championships twice, eventually defeated China's Pang Qianyu 5-4.

"I usually lead first but my opponents overtake me quite often," said Mukaida. 

"It was the other way around, I was behind.

"I had the resolution to win at the end. 

"The strong emotion is what made me win this match.

"First, I couldn't tackle her like I always do. 

"But in the six minutes I was able to do my style of wrestling with a very strong determination to win.

"Pang was very strong, I wanted to beat her, and I was determined to get a gold medal. 

"I continued to have that feeling throughout the six minutes."

Vanesa Kaladzinskaya of Belarus and Bat-Ochiryn Bolortuyaa of Mongolia won bronze medals.

Zaurbek Sidakov won the ROC's second Tokyo 2020 gold in freestyle wrestling as he captured the 74kg title.

The 25-year-old added the Olympic title after winning the last two World Championship gold medals back-to-back, after comfortably seeing off Mahamedkhabib Kadzimahamedau of Belarus 7-0.

When he was eight, Sidakov was evacuated from his school in Beslan after it was taken over by Chechen terrorists.

The three-day siege in 2004 resulted in the deaths of 334 people, more than half of them children.

"This gold just reminds me of all the hard work, all the sweat that I've dropped in training for this," said Sidakov. 

"I'd like to thank everyone who supported me through the hardest parts of the job. 

"My coaches, my family, my friends, everyone.

"This gold medal means I've got the best success in my sport and I can't really express my feelings right now."

Bronze medals went to back-to-back and reigning 79kg world champion Kyle Dake of the US, and Uzbekistan's Bekzod Abdurakhmonov.