Britain’s multiple world and Olympic champion held off the challenge of his training partner, home athlete Bashir Abdi, to set a new mark of 21,330 metres - eclipsing the 21.285m set by Haile Gebrselassie in 2007, with Abdi finishing just eight metres behind.

Hassan’s record in a stadium lacking supporters but not noise - thanks to the controlled recordings of crowd sounds from past meetings -  also came after a titanic battle, in this case with Kenya’s world marathon record holder Brigid Kosgei.

Both women moved to more than a minute inside world record pace, although it later transpired Kosgei had been disqualified for stepping onto the infield with seven minutes of the race remaining. 

It seemed a very harsh decision for what was a momentary slip of the left foot that did the reverse of bringing any advantage.

The Dutch world 1500 and 5,000m champion reached 18,930m as the hour elapsed, beating the existing mark of 18,517m set by Ethiopia’s Dire Tune in 2008 after getting away from Kosgei with a final, wild, arm-pumping sprint.

As the men’s race moved into the final quarter of an hour, the ghostly figure of the current world record holder, Gebrselassie, was shown on the screen images in virtual shape, running at their side. And they were bang on the pace.

With 10 minutes to go they moved ahead of the world record schedule, passing 18,000m in 50min 42:07sec.

Inside the final five minutes Abdi, who the day before had confessed that he expected Sir Mo to beat him, moved to the lead, but the multiple champion was shadowing him still.

As advertised, the Wavelight visual pace-guidance system employing differently coloured LED lights installed on the inside edge of the track made the pursuit of records on the night immediately intelligible.

With three minutes remaining, both men were 30 metres clear of the leading blue lights, showing the intended pace, and the green lights snaking behind them, showing the actual world record pace.

A second world record appeared in the offing - and the same question was being asked as in the earlier women's race - who would break it?

As the gun was fired to signal  a minute to go, the Briton made his decisive move and by the time he entered the home straight for the final time he had the race won.

As the final seconds ticked away he secured his victory, and world record, at almost exactly the same spot where Hassan had earlier triumphed. Taking a few seconds to realise it was all over, he ran on until the stadium announcer told him: "The world record is yours, Mo!" 

It was the 37-year-old's first officlal world record in his long and successful career - he set an indoor world mark for two miles in Birmingham five years ago but that did not have official world record status.

Later Sir Mo explained that he had noticed there were 24 seconds left as he went over the finishing line for the last time, but that he had been unable to see another clock so had kept on running just to be sure of the record.

He added that he and his training partner had deliberately run at a steady pace for the early part of the race before feeling ready to accelerate, and it was a plan that worked perfectly.

Abdi had the consolation of lowering Gebrselassie's world mark for 20,000m from 56min 26sec to 56:20.02 having led his friend at that point.

He assured reporters afterwards that this was not deliberate - "I had gone to the front to help, to make sure we kept on the world record pace," he said.

There was doubtless an additional savour to the record for Sir Mo, given his huge public bust-up with Gebrselassie during last year’s London Marathon build-up, when he alleged he had had property stolen while staying at one of the Ethiopian legend’s hotels.

Kenya’s Olympic 1500m champion Faith Kipyegon had to settle for another near miss as she attempted to beat the world 1000m record of 2min 28.98sec set on this track in 1996 by Russia’s double Olympic champion Svetlana Masterkova.

Having finished just 17 hundredths of a second short at last month’s opening Diamond League meeting in Monaco, Kipyegon seemed on track to achieve her ambition with 200 metres remaining, but faltered slightly over the final few metres to cross the line in 2:29.92.

Norway’s 19-year-old European 1,500m champion Jakob Ingebrigtsen, who has already reduced the European record to 3:28.68, made a bold effort to improve on that but his honourable solo effort saw him finish in 3:30.69, with Jesus Gomez of Spain a distant second in 3:34.64.

Just over an hour before the men’s pole vault event got underway, Britain’s 24-year-old Harry Coppell, gold medallist at the 2013 World Youth Championships, announced his intention of joining the big boys of the event by setting a British record of 5.85m in Manchester.

That effort took the Briton up to sixth in the 2020 world rankings.

Back in Brussels the competition took on familiar shape as Sweden’s 20-year-old world record holder Armand Duplantis saw the last challenger, home vaulter Ben Broeders, fall away with a best of 5.70m.

Sweden’s 20-year-old European champion then went on to clear 6.00m at his first attempt before having another crack at 6.15m, a centimetre higher than the best outdoor clearance ever made, by Sergey Bubka in 1994, but he failed to make it this time.