Double gold medallist and defending champion Alistair Brownlee was left out of the British team. 

He had struggled with an ankle injury and was actually disqualified from one race for ducking a rival. 

He will instead seek election to the International Olympic Committee’s (IOC) athletes’ commission.

Jonny followed his brother home for bronze in 2012 and silver in 2016 but is the senior British triathlete this time.

Alex Yee was selected at Alistair’s expense. 

He had been a spectator in 2012 and watched their Rio 2016 race on television.

"I definitely struggled with a bit of imposter syndrome and not feeling like I was quite worthy to stand on the start line with those guys," Yee said.

"The Brownlees are probably the two greatest athletes our sport has ever seen, certainly in Britain, and to be a name beside them is a huge honour."

The absence of the champion means the race could be the most wide open for a decade. 

Rio bronze medallist Henri Schoeman of South Africa is set to take his place on the start line for a start at 6.30am local time to counter the heat.

He won Commonwealth Games gold in 2018 on Australia’s Gold Coast.

London 2012 silver medallist Javier Gomez Noya of Spain missed Rio after fracturing his arm in a bike accident but is set to compete at the age of 38 in Tokyo.

"I wish I was a bit younger to be a bit better, but I still think I have my chances," Gomez said.

 "I’ve been training very well, the times are there in each training session, swimming, biking and running, so I think I can do well. 

"I’ve done everything in my career, this is just a bonus and I’m gonna go for it.

"The heat is going to be an important factor in the race, so I’ve been training in Cozumel in Mexico for the last few weeks, trying to get used to these conditions which are pretty similar, if not hotter."

Frenchman Vincent Luis, winner of the World Triathlon Series over the last two years, is aiming to become only the second person after Brownlee to win the Olympics as a world champion.

“It’s my third Olympics," Luis said. 

"It started with London, Rio and here we are in Tokyo. 

"It was a tough journey, a lot of injuries and a lot of setbacks, but these past four years have been good for me, and I’m quite happy to be fit on the start line and give it my best. 

"Mentally and physically, I’m ready," Luis said.

His triathlete girlfriend Taylor Spivey will be missing from the women’s race on Monday as she was not selected for the USA team.

"It was hard for us, but now she’s incredibly supportive, and I can’t thank her enough for that," Luis added.

"She told me to go and bring back a medal for us, so that’s exactly what I am going to do."