Quarter-of-an hour later,  as day seven at these Championships moved into the early hours of day eight, Britain’s Katerina Johnson-Thompson made a similar breakthrough, defeating Belgium’s European, defending and Olympic champion Nafissatou Thiam to the heptathlon title.

She also broke the British record of 6,955 points, set by Jessica Ennis-Hill at the London 2012 Olympic Games, with her total of 6,981 as Thiam, troubled by an elbow injury, took silver on 6,677.

The bonze went to Austria’s Verena Preiner on 6,560.

The final action of the morning saw Germany's world under-20 champion Niklas Kaul earn the decathlon title with victory over 1500m, following the withdrawal through injury of France's defending champion Kevin Mayer, with Miller-Uibo’s husband, Estonia's Maicel Uibo, securing another silver for the family collection - equally unexpected, but in a different way.

After totalling a personal best 8,604 points to finish ahead of the 8,529 accrued by Canada’s Rio 2016 bronze medallist Damian Warner, Uibo - his shoulder plastered up, swaying and grimacing - provided a complete contrast to his wife.

She sat, stunned and calm, draped in the Bahamian flag, after taking more than half-a-second off her Americas record with a time of 49.37 and finding it was only enough for silver.

Naser, 21, took nearly a second off her personal best of 49.08 in an astonishing display.

The Bahrain athlete won world silver two years earlier in a race where Miller-Uibo had stumbled out of the running, but such has been her dominance over the past two years that very few people thought she would be denied, especially as, unlike the Championships two years ago, she was focusing her attention on the single lap.

The super-fast nature of this final was underlined by the fact that the three runners behind the 25-year-old Bahamian also set personal records.

Shericka Jackson of Jamaica took bronze in 49.47, Wadeline Jonathas of the United States was fourth in 49.60, and her compatriot, defending champion Phyllis Francis, fifth in 49.61.

This was always a duel between two runners - one apparently in her prime, the other apparently reaching it.

When Naser, in lane five, went out so fast she was challenging her rival in lane seven around the top bend, it seemed she was searching for some way to vary the pattern of the last two years by taking the race to Miller-Uibo.

It turned out to be far simpler than that…

"I’m really short of words to describe how I’m feeling, it’s just crazy," said Naser.

"I’m screaming, I'm so happy.

"It's been so tough with all the training and injuries, and getting there has been hard.

"I didn't want to chase because I'm so used to chasing all the time, so I had to go out fast, and I just kept going.

"To cross the line and see that I am world champion in that amazing time, I just couldn't believe it."

Asked if she might contemplate breaking the world record of 47.60 set in 1985 by Marita Koch of East Germany, she responded: "Anything is possible."

Miller-Uibo commented: "To run a time like that and not to win is incredible. 

"I think I let her get away from me a little too much but I got a huge personal best so I have to be happy with that. 

"She ran a crazy race.”

Johnson-Thompson held a lead of 96 points over Thiam from day one, her first day total of 4,138 points being the fourth best ever achieved.

The first of the final three events saw her consolidate that lead as she produced a long jump of 6.77 metres, while Thiam registered a best of 6.40m after taking off 33 centimetres before the board.

That healthy addition of 1,095 points extended the Briton's lead to 216 points as they headed towards the penultimate event, the javelin, traditionally Johnson-Thompson’s weakest.

But Thiam was clearly struggling with an elbow injury that had surfaced ahead of these Championships and was heavily strapped as she fouled on her first attempt.

Johnson-Thompson took advantage, producing a personal best of 43.93m with her second attempt.

Thiam, having carefully re-taped the elbow of her throwing arm, responded like a champion to register 48.04m. 

But she needed more, as the Briton was still 137 points ahead.

Johnson-Thompson pushed on in the 800m to set another personal best of 2min 07.26sec to add the world outdoor title to the indoor version she won last year.

Three personal bests on the opening day had put Mayer in third place overnight, but well placed to move past his Canadian rivals on his traditionally strong second day.

He finished second fastest in the day's opening 110m hurdles in 13.87 to move up to second place with 5,474 points, behind Warner, top of the list with 13.56, who extended his lead on 5,545.

It soon became obvious the defending champion, with much strapping on his leg, was struggling, and although he moved into the overall lead with 6,310 points after the shot put, where he managed the fourth best distance of 48.34m, that was his high watermark.

Before the pole vault, he defiantly whipped up the crowd - but his face was full of suppressed emotion.

After five or six strides he abandoned his first attempt, leaning his face down into the pole for a few moments.

Again he tried, but after five steps, in obvious pain from the left leg bandaged beneath the calf, he discarded the pole and sank tearfully into the pit.

The man who had described the staging of these Championships as a "disaster" had suffered his own personal trauma.

After the champion's departure, the 21-year-old Kaul seized his chance.

A 5.00m vault was sufficient to set him up for his strongest event, the javelin, and he fulfilled expectations with a best of 79.05m, which meant he had only to run to form to win the 1500m and overall title.

He did so, clocking 4:15.70 for a personal best of 8,691 points.

Gong Lijiao of China successfully defended her world shot put title, securing a medal at these Championships for a sixth successive time, with a fourth round best of 19.55m.

Lijao was almost beaten by Jamaica’s Daniell Thomas-Dodd, whose fifth effort thudded on the 20m line, only to be ruled out for a foul, and who waited in suspense on her good-looking final throw, before having to accept silver when it came up as 19.47m.

Bronze went Germany’s Christina Schwanitz on 19.17m.

Another medal was awarded on the day as a second protest from Spain over the fall by Jamaica's defending 110m hurdles champion Omar McLeod, which knocked Orlando Ortega out of medal contention, was upheld.

The former Cuban was awarded an extra bronze.