It has taken a series of plot twists worthy of a Hollywood thriller. But now, staggeringly, the world championships has the showdown between Wayde van Niekerk and Isaac Makwala, the usual suspects in the 200m and 400m all season, it has craved all along.

First Makwala illustrated powers of recovery worthy of Lazarus to lift himself off his sick bed to qualify for the 200m final with two stupendous runs in the space of two hours. Then Van Niekerk, desperately weary after winning the 400m final and chilled to the bone by the London weather, struggled through to join him as a faster loser in his heat.

But what makes the story even more remarkable was that until Wednesday lunchtime Makwala was not even in the 200m, having been banned from running in Monday’s heats and placed in 48-hour quarantine after throwing up and being diagnosed with a suspected case of gastroenteritis.

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That means he could only watch as his South African rival took gold. But, with his quarantine spell over and following the approval of London 2017 doctors, he was given an unexpected reprieve by the IAAF, which allowed him to compete in a solo time trial for a semi-final place.

Still, the odds were stacked against him. The stadium was barely a quarter full. The temperature was in the low teens. And the driving rain, which had covered London like a soggy blanket all day, was putting in a triple shift.

It was not the weather for running fast. Yet with the crowd urging him on, Makwala stormed home in 20.20sec – well inside the 20.53 needed to qualify.

His route to the final still looked thorny, however, given he was put into lane one – the worst in the race – in his semi-final. Again, he made light of it, coming home in 20.14 just behind the American Isaiah Young.

When he crossed the line he put his hands in the air in triumph. No wonder. After all he had been through, this must have felt like a triumph.

Not that the Botswanan is entirely happy. “I’m running with anger and I still want my 400 metres, that’s my race. I wish to thank the IAAF for giving me another chance and the British crowd is so amazing. But I wish the IAAF had taken the decision for me to run my 400m first because that was the race I was training for.”

How Makwala recovers from two hard races in two hours and a bout of sickness is an open question but he knows Van Niekerk is probably even more tired given how much he struggled and strained before coming home in 20.28. What’s more, he will be running his sixth race in seven days in Thursday’s final.

It may be that someone like the Trinidad and Tobago athlete Jereem Richards or the Turk Ramil Guliyev, who looked good in winning their semi-finals, springs a surprise. Britain’s Nethaneel Mitchell-Blake, who made it through as a fastest loser, can also not be discounted.

Mo Farah made it through to Saturday’s 5,000m final with a minimum of fuss after finishing second to Yomif Kejelcha in 13min 30.18sec.

While he looked comfortable in doing so, he admitted his legs were still feeling the after-effects of the brutally tough 10,000m final in which he won gold last Friday.

“I was cold and miserable out there but it’s job done,” he said. “I was a little bit beaten up but I’m OK and glad I’ve come through.”

Farah is now eyeing a staggering fifth successive 5,000m and 10,000m double at a major championships, going back to the London 2012 Olympics.

He admitted the shock defeat of his close friend Usain Bolt in the 100m final showed the dangers of taking anything for granted.

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“It ain’t easy,” he said. “We’ve seen it with Usain Bolt. It happens. I was looking forward to seeing him win but it didn’t happen. No one’s going to give it to you, no matter who you are, even Usain Bolt. He’s a human being at the end of the day and I now have to focus on myself and get ready.

“The double would be pretty amazing. It would mean the world to me but at the same time I ain’t taking anything for granted. Those boys are coming for me. You can see it in the heats, they’re out to prove a point and show me. I’m going to do it, I’m going to do it. You’ll see me at the start line. I just have to recover.”

In the second semi-final, one of Farah’s biggest rivals for gold, the American Paul Chelimo, survived a mid-race fall to qualify. Chelimo, who won 5,000m silver in Rio, was able to make up a 40-metre deficit to qualify as a fastest loser behind the exciting 17-year-old Ethiopian Seleman Barega.

Britain’s Andrew Butchart also made it through as a fastest loser.