Boyce had previously produced a Championship high finish of 16th at the Europeans in Zurich five years ago, and decided on iced socks and a scrum cap to keep his head warm in the opening exchanges on the Corniche waterfront in Doha for the 11:30pm start.

Japanese Yusuke Suzuki set the early pace, as he had done for the London Olympics, where he fell down the field to finish 36th.

Suzuki had a ten-second lead established over France’s defending world champion Yohann Diniz and Slovakia’s reigning Olympic champion Matej Toth after five kilometres, but in a time almost two minutes slower than the corresponding split time at the previous Worlds in London two years ago.

Boyce was 19th at that first major checkpoint, alongside Canadian Evan Dunfee, the fourth-placer from the Rio Olympics.

By the 10km mark, Suzuki and Diniz had opened up a 15-second lead on a chasing pack of three containing Toth. Boyce was 81 seconds down in 17th.

But from there, Diniz slid down the pack, losing a minute and a half on Suzuki over the next 5k, with Boyce part of a group of three with Dunfee and Portuguese João Vieira maintaining their position -Boyce was 16th at 15 kilometres.

The trio were closing in on the world record holder before the Frenchman’s exit one kilometre later.

Three-time European Champion Diniz – who had accused athletics bosses of treating road athletes like “idiots” on the eve of the race as opposed to the track and field athletes competing in the air-condition Khalifa Stadium – said afterwards: “I was tired and exhausted straight away from my breathing.

I had no legs. I tried to keep up with the pace which was not very fast. I accelerated five seconds per kilometre, but could not find the rhythm.

After seeing 28 starters succumb to the thumping overnight heat and humidity in Doha the night before in the women’s marathon, Diniz admitted: “I knew there would be extreme conditions, but for me it was too much. My body could not do it. I did not want to go that far.”

With big names therefore beginning to succumb, Boyce was keeping himself as cool as possible in the Qatari capital, dispensing with the scrum cap before tackling the final two-thirds of the contest.

Boyce, Dunfee and Vieira stayed together for a considerable amount of time, with Boyce passing the 20km and 25km marks in 14th place, as Suzuki opened up a two-minute lead over the rest that had increased to three minutes 16 seconds by the 25km halfway point.

Toth had fallen back to tenth, almost four minutes down on Suzuki, when his race came to an end at 29 kilometres.

But Finn Valley AC's Boyce was still going, hitting the top ten at 30km, as Suzuki’s nearest challengers were the Chinese duo of Luo Yadong and Niu Wenbin, exactly three minutes behind the Japanese leader.

Vieira had moved up the road slightly by this stage but Dunfee was still alongside Boyce as he had been for the entire race up to that point.

The attrition rate was increasing, and further athletes were falling away – Norwegian Håvard Haukenes was tilting for the medals before he received his race-ending fourth red card inside the final 20km - and suddenly, Boyce was up to seventh with 15km to go, two minutes outside the medals.

Suzuki was three-and-a-half minutes clear of Niu and Luo at this point, and maintained that gap until five kilometres to go, when he started to suffer quite noticeably, deciding to slow down to a virtual standstill each time at the water station to take a badly-needed cool drink.

While the leader’s position was in peril, Boyce kept moving on up, and was sixth with ten kilometres to go, only 87 seconds off bronze, with second-placed Niu on three cards and Luo beginning to fall down the field to a point where Boyce could actually see him.

Dunfee was also never more than twenty seconds clear of the Irishman, who was now a live medal contender.

With five kilometres left, Boyce was still sixth, but tightening the gap – Luo had been overtaken by Dunfee at this point for fourth-place, with Vieira about to shoot past Niu to go second.

Suzuki’s gap was also being eaten away every time he stopped moving his feet to take a drink.

Every medal was at risk, and there was no guarantee for any of the five men ahead of Boyce in the closing stages that any of them would actually finish.

But Suzuki had calculated well, taking the world title in a remarkable time outside of four hours - 4:04:20 – finishing 39 seconds clear of Vieira, the Portuguese becoming the oldest World Championships medallist ever at the age of 43, finally winning his first Worlds medal at the eleventh attempt, having made his debut in Seville in 1999.

Canadian Dunfee overhauled the backtracking Niu to finish third for his first global medal, in 4:05:02.

The two Chinese athletes who looked at one stage like they might catch Suzuki, Niu and Luo, finished fourth and fifth respectively.

Having a large margin over those behind him, triumphant Boyce took a couple of extra seconds to confirm his heroic sixth place finish by stopping, turning, and literally moonwalking over the line.

His finishing time of 4:07:46 was well outside his personal best – just like everyone else.

However, the Irishman had a healthy gap of three minutes over the next athlete behind him, Carl Dohmann of Germany.

Boyce admitted afterwards to Athletics Ireland social media: “It was actually easy for 40km because I had completely zoned out. This was a training session, forget about it.

World Championships? This was just a 40km training session and a 10km race.

“I was already quite near, about eighth or ninth place at 40km. I was thinking about picking people off at that point.

“The race plan was perfect. Rob (Heffernan) helped me out, and made sure I was fully confident in what I was doing the whole race. I was getting feedback all the time and everyone was just back on on the day.

“The strategy was perfect and so was the result.

Our training was so good, it didn’t matter what the conditions were – I was going to be top six or top eight.

“It was just the fact we got everything else spot on that the result came.”

Referring to World Championship winner Heffernan being his coach, Boyce enthused: “It’s invaluable to have probably the best male athlete in the country, and even his coach Robert Korzeniowski, who was three-time Olympic champion was on the phone constantly.

“So who am I to argue with two of the greatest world champions in history?”

Boyce, who finished 19th in last year’s European Championship in Berlin after his 16th place in the 2014 edition in Zurich, was in the field for his fourth World Championships.

But the previous three had only produced one finish – 25th in Moscow in 2013 on the day his now coach Rob Heffernan was crowned world champion.

Boyce’s sixth-place finish puts Ireland on the placing table for top-eight finishes right at the start of the Championships, whereas the country had to wait until the very last day in London for Heffernan to make it happen.

Helsinki in 2005 was the last time Ireland failed to get a top-eight finish at the World Championships.

The women’s 50k walk was won by China’s Liang Riu in 4:23:26, enjoying a three-minute winning margin over compatriot Li Maocuo, with Italy’s Eleanora Giorgi claiming bronze in 4:29:13, crossing the line seconds before 4am, and declaring after the race: “Everyone here tonight, we are all warriors.”

On the track earlier, Thomas Barr missed out on a place in the 400m hurdles final by 0.09 seconds, ranked tenth overall having finished fourth in his semi.

But Mark English bowed out in the first-round heats of the 800m, having narrowly missed out on automatic qualification for Doha.

A controversial American 1-2 was the outcome of the men’s 100m final as Christian Coleman took gold in a world lead 9.76 seconds ahead of 38-year-old outgoing champion Justin Gatlin in second.

Canadian Andre de Grasse was third in 9.90 seconds, 0.01 behind Gatlin.

Sifan Hassan of the Netherlands won the women’s 10000m in a tremendous finish, clocking a world lead 30:17.62 ahead of long-time Ethiopian leader Letsenbet Gidey and Kenya’s Agnes Tirop third.

The top five all set new lifetime bests.

An upset in the men’s long jump saw Tajay Gayle take Jamaica’s first ever World Championships field medal, and it was gold.

He cleared a world lead 8.69 metres to see off American Jeff Henderson in second (8.39), with exciting Cuban Juan Miguel Echeverria third (8.34).

London champion Luvo Manyonga was fourth on 8.28 off the back of his Irish all-comers record at last month’s Cork City Sports.

A tight women’s hammer went to DeAnna Price of the USA, whose best throw of 77.54 metres was 1.19m clear of silver-medallist Pole Joanna Fiodorow’s PB-breaking 76.35m, which came in the opening round.