The former decathlete, in his first full season in the event, left American Olympic champion Kerron Clement trailing in his wake as he led from the gun and crossed the line with wide-eyed shock written across his face.

On a dramatic evening, Bahamian Shaunae Miller-Uibo fell apart in the final 10 strides to go from first to fourth and let American Phyllis Francis chase through late for 400m gold, 19-year-old Salwa Eid Naser grabbing silver for Bahrain ahead of American multiple world and Olympic champion Allyson Felix.

Botswana's Isaac Makwala had earlier battled through both a solo time-trial and a semi-final just two hours later to make a 200m final that seemed impossible when he was excluded from Tuesday's heats on medical grounds.

With Britain's Mo Farah safely qualifying for Saturday's 5,000m final, it was Warholm's blistering display that deservedly grabbed the headlines, his nation's first gold at the Worlds since Ingrid Kristiansen took the 10,000m title in Rome 30 years ago.

The 2015 European junior decathlon silver medallist defied his tender years and the experience of the men around him as he judged his effort to perfection in the most brutal of events.

As always he went out hard, but even with Turkey's Yasmani Copello and Clement chasing him down, stayed strong in the home straight, finishing in 48.35 seconds with Copello taking silver and Clement bronze.

"I truly don't believe it," said Warholm. "I've worked so hard for this but I don't know what I have done. This is an amazing feeling. I'm world champion, that's crazy."

Miller-Uibo seemed to have her own final in the bag as she maintained her lead over a fading Felix into the final 30 metres.

The Bahamian then appeared to pull a muscle, her left foot catching on the track as all her momentum died.

Francis came charging through to take advantage in a new personal best of 49.92secs, Nasser in her wake for an exceptional silver and Felix, so often the darling of these championships, forced to settle for third.

Farah stays on course for double

Farah's 10,000m gold on the first night of these championships is Britain's only medal so far, but if there is added pressure on his slim shoulders in his last major track final, it did not show.

In relentless heavy rain, Farah showed little sign of fatigue after his exertions at the end of last week, navigating his way through a slow heat that saw the 16-strong field bunched for much of the race.

With only the first five across the line guaranteed to qualify, the four-time Olympic champion stayed out of trouble at the front, working down the home straight to finish an easy second behind Ethiopia's Yomif Kejelcha in 13 minutes 30.18 seconds.

"I'm cold, it's miserable out there but it's job done," said Farah. "I had to get back into some kind of running again. It's been five days of chilling out and recovering.

"The 10k did take a lot out of me and I'm a little beaten up but I'm OK, I'm glad I've qualified and will get ready for the final."

Scot Andy Butchart's seventh in the second heat in 13:24.78 saw him join Farah as a fastest loser on another mixed night for British athletes.

While Nethaneel Mitchell-Blake's 20.19secs was enough to get him into Thursday's 200m final as the first fastest loser, neither Danny Talbot nor Zharnel Hughes could get through their respective semis, Talbot unable to back up the personal best he set in his heat.

China's Gong Lijiao wins women's shot put

South African 400m champion Wayde van Niekerk was also relieved to wriggle through as a fastest loser, third place in the third semi behind Turkey's Ramil Guliyev and American Ameer Webb as Christophe Lemaitre of France went out in fourth.

British Commonwealth silver medallist Nick Miller was an automatic qualifier for Friday's hammer final after throwing 75.52m, two centimetres beyond the required mark. Only Lorraine Ugen, of the three Britons in long jump qualifying, will be back to contest the medals in two days' time.

Ugen's 6.63m in horrible conditions saw her behind only Russia's Darya Klishina and American Tianna Bartoletta. Britain's Shara Proctor was one place shy of making the final with 6.45m for 13th and compatriot Jazmin Sawyers back in 20th with a best of 6.34m.

And Gong Lijiao of China took the shot put final from Hungary's Anita Marton and American Olympic champion Michelle Carter with her 19.94m in the penultimate round.