He eventually won in a time of 1 hour 45min 4sec to claim Norway's first Olympic medal in triathlon and their first of any colour here at Tokyo 2020.

The race began at 6.30am local time to counter the Tokyo heat, but started in chaotic circumstances at Odaiba Marine Park.

There was a false start at the beginning of the swim when a boat got in the way of some athletes.

Little more than a second had separated the top ten triathletes for much of the race and, as the running transition came into the last 2,500 metres, it was still Yee who held the advantage.

"I don't really have the leg speed if we came down to the blue carpet," Blummenfelt said.

"I had to drag it out five minutes away from the finish line and go really, really hard for five or six minutes and hopefully that would be enough to break them.

"It was a good feeling when I saw that there was a gap and I just had to make sure that it was big enough even for the last 200 to 300 metres."

Blummenfel finished 11 seconds clear of Olympic debutant Yee, who had to settle for silver in 1:45:15. 

"I knew my strength was in my leg speed, just trying to tease the bits where I could pick up my leg speed," said Yee, who wanted to succeed compatriot Alistair Brownlee, the winner of the last two Olympic races, as champion.

"I tried to play to my strengths.

"I was pleased to come away with second, honestly.

"I timed it a bit wrong and left it a bit late to close the gap, but Kristian was the man on the day."

New Zealand's Haydn Wilde claimed bronze in 1:45:24.

"There were some absolute animals in that group," he said.

"It could have been anyone's game. 

"After a few attacks, it was left to the last three of us, we all had poker faces on behind our glasses."

The false start occurred because the boat provided for the media was allowed to move too close to the pontoon. 

Jet-ski riders had to intercept at least 12 swimmers after the restart was ordered for the race.

"I saw the boat on the left side and found it quite strange that the starting bell came," Blummenfelt said.

"I felt that the boat was still in front of the left side of the pontoon, so when I jumped in, I thought that this would most likely be pulled back and go for another start.

"I just tried not to go too slow but keep a little bit left, and I look at it in a positive way that I actually got a little warm-up before the start."

The women's race is tomorrow.