The 27-year-old defeated China's Rio 2016 gold medallist 21-15, 21-12 to become the first European winner of the Olympic title for 25 years.

Axelsen was brilliant in both attack and defence as he found winners when the opportunities arose while regularly keeping the door closed for Chen.

His victory sees him follow in the footsteps of fellow Dane Poul-Erik Høyer, now the President of the Badminton World Federation, who won the title at Atlanta 1996.

Since then the gold has exclusively belonged to Asia, with Chen hoping to repeat the feat of Chinese great Lin Dan by successfully retaining the prize.

Thirty-two-year-old Chen has listed Lin as one of his heroes but could not double up as his idol had done at Beijing 2008 and London 2012, and the 2014 and 2015 world champion must settle for silver.

For Axelsen, the 2017 world champion, the result reverses the Rio 2016 semi-final where he was beaten by Chen before going on to defeat Lin for bronze.

He remarkably did not drop a game throughout the tournament here, while his build-up to Tokyo 2020 was blighted by a series of injuries.

In September, he had surgery on his right ankle and he had to pull out of the 2019 World Championships due to "persistent back and leg pain".

Axelsen also missed six months of the season in 2018 due to asthma issues and injuries to both ankles, while he had to withdraw from the European Championships in May following a positive COVID-19 diagnosis when he had already reached the final.

The Dane later shared a video of him flying home from the tournament completely encased in a plastic tube.

"When I won the last point I couldn't think, I couldn't feel anything, I could only feel a big rush of adrenaline, of happiness, that all the hard work is worth it," Axelsen, who was seeded fourth, said. 

"This is the biggest dream of mine coming true, I simply can't believe it.

"I think you can say that I've been at my absolute best. 

"When you win an Olympic final in straight games like this against Chen Long, you've been at least really, really close to your best, I'm so happy."

Chen, who was the sixth seed, now has a full set of Olympic medals after winning bronze at London 2012.

Bronze this time went to Indonesia's Anthony Sinisuka Ginting, who beat Guatemala's tournament surprise package Kevin Cordon 21-11, 21-13.

This was Indonesia's second badminton medal of the day after Greysia Polii and Apriyani Rahayu won the women's doubles final by beating China's second seeds Chen Qingchen and Jia Yifan 21-19, 21-15.

Two South Korean pairs contested bronze with Kim So-yeong and Kong Hee-yong seeing off fourth seeds Lee So-hee and Shin Seung-chan 21-10, 21-17.

Polii was one of the players disqualified from London 2012 after a huge scandal which saw doubles teams accused of losing in a bid to manipulate the draw.

"Twenty years ago when I was 13-years-old I knew that Indonesia hadn't made any history in women's doubles," she said, after becoming one half of her country's first gold medallists in the event. 

"I know that I was born to be a badminton player, and I have that fate. 

"I was 13-years-old, and I really wanted to make history for Indonesia in women's doubles.

"God has given me the dreams and the fate into my heart. 

"The people said 'you're not going to make it because Indonesia doesn't have any history for women's doubles'. 

"And we know that China, Korea, they are the stronger. 

"When you say in 2000, 'who wants to beat China?' 

"It was nobody, not even Korea."

Polii added: "The Olympics in London broke my heart. 

"So many people in Indonesia and my family said, 'don't give up'.

"They keep trusting me. 

"And then the breakthrough is coming. 

"Day by day, year by year."