Germany's Jonathan Hilbert, a long-time part of the chasing pack, moved away to cut the lead and take the silver medal in 3:50:44, with Canada's Evan Dunfee, controversially fourth at Rio 2016, timing his final effort perfectly to claim bronze in 3:50:59.

The 20th and last Olympic staging of this event - which is being replaced by an as-yet unspecified mixed team event at Paris 2024 - began at 5.30am local time in Sapporo, with both the timing and the location, chosen over Tokyo last year, being designed to mitigate the conditions for competitors.

By 8.30am the conditions at the start of the race - 25.7 degrees with humidity at 79 per cent - had become 33 degrees and 55 per cent humidity.

That made the resolve and enterprise of Tomala appear all the more remarkable.

Having finished 19th at London 2012 in the 20km race walk, the Pole switched to the longer distance relatively recently and this was only his third 50km race.

He failed to finish in his debut at Dudince in 2017, but returned to the Slovak city this year, clocking 3:49:23 to finish fifth.

Tomala tracked down Finland’s leader Veti-Matti Partananen shortly after the halfway point and had established a nine seconds lead as he passed 30km in 2:21:21.

By 35km his lead over the group had extended to 1min 46sec as he went through in 2:42:34.

By then France's 43-year-old world record holder Yohann Diniz, seeking a first Olympic medal in a career that has seen him earn world gold and silver and three European titles, had dropped out.

Dunfee, a long-time vocal proponent of clean sport, was a hugely popular medallist.

At Rio 216 he was bumped by Hirooki Arai in a battle for bronze, with the Japanese walker finishing third.

Arai was then disqualified for making contact with Dunfee, only to be reinstated on a further appeal.

At which point Dunfee advised the Canadian team from making its own further appeal, saying: "I believe the right decision stood."

Tomala thus becomes the second Pole to win this title after his illustrious forbear Robert Korzeniowski, winner of the gold medal at Atlanta 1996, Sydney 2000 and Athens 2004.

Australia's Jared Tallent received the London 2012 gold medal belatedly after he had finished second to Sergey Kirdyapkin, one of three Russians whose results were annulled because they had been doping.

Matej Tóth of Slovakia, the Rio 2016 gold medallist, finished 14th today in 3:56:23.

"It was an amazing day for me - I can’t believe it," said Tomala.

"I work for it my whole life since I was 15 when I thought for the first time during training I would like to be a [Olympic] gold medallist.

"This was only the second 50km in my life, and I win the Olympic title – crazy, right?"

Asked why he had moved up from 20km, he added with a laugh: "I was bored - I needed a new challenge.

"I thought the 50km would be good and now I know it is.

"Why 50km? 

"Because we have the best walker in history, Robert Korzenkowski.

"He is a legend and now I achieve [my own piece] history.

"The first 30km was so easy for me, it was easy like slow training.

"So I was thinking maybe we can do something…"

Dunfee, 30, who also won bronze at the 2019 World Championships in Doha, commented: ""y body gave me everything today - it is more than I could ever ask for.

"My hamstring wasn’t happy with me that last six to eight k (kilometres).

"I kept asking for a little more, and it just kept saying, this is all you have.

"Coming around that last bend I asked for a little bit more.

"I thought about my parents, my friends, my nana who isn’t here.

"I thought of her.

"She always used to say [I had] wings on my feet.

"I don’t need a medal to validate myself.

"But I’m proud of what I accomplished today - I have been dreaming of this moment and winning this medal for 21 years.

"Hopefully, today means we can stop talking about Rio.

"I loved that moment [finishing fourth] because it has given me a huge platform.

"It has allowed me over the past five years to be able to speak to over 10,000 school kids in my local community and talk about the value of sport and what sport has turned me into.

"Growing up I was one of those the kids who wanted to win.

"I defined myself by whether I won or lost, I was an a**hole, a sore loser.

“I was the kid that broke hockey sticks if I lost.

"I defined myself by winning or losing.

"Sport helped me grow and change and transform into someone who in Rio could say, 'No, I don’t need a medal to validate my success'."