Matt Hudson-Smith won his first World Championships medal, claiming 400m bronze with a gutsy run in Eugene.
The Briton, 27, went hard over the first 300m and then held off American rival Champion Allison and world record holder Wayde van Niekerk to take the final podium spot.
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Michael Norman, of the USA, won gold in 44.29 seconds, ahead of Grenada's London 2012 champion Kirani James.
"This is just the beginning," Hudson-Smith, who ran 44.66, told BBC Sport.
"I don't think I have scratched the surface, if anything. I have got a monkey off my back getting a world medal. Now I push on from here."
In the wake of Norman's victory, the American crowd cheered Sydney McLaughlin to 400m hurdles victory in a stunning new world record time.
It was on the same Hayward Field track that Hudson-Smith broke Iwan Thomas' 25-year-old British record with a 44.35-second run in May.
However, the Englishman has always been adamant that he needs medals, not landmarks, at this point of his career.
At the age of 21, Hudson-Smith finished eighth in the Rio 2016 final, but came close to quitting the sport a year later, contemplating a career in strength and conditioning.
His mother convinced him to continue and he left his home city of Wolverhampton to train in the United States.
He missed last year's Olympics with the latest in a string of medical problems, but has returned in fine form this season.
He qualified second-fastest for the final before finally adding another medal to his 2018 European gold.
"It's mad," he added. "I don't think people know the half of it. These past three years have been a whirlwind - Achilles tendon tears, hamstring tears, a lot of mental health issues.
"I was just hanging on for dear life at the end there."
Hudson-Smith will return home to compete at the Commonwealth Games in Birmingham where, with James opting to miss the Games, he will be favourite in front of a home crowd.
Hudson-Smith's medal is Great Britain's fourth of the Championships following Jake Wightman's 1500m gold and bronzes for Laura Muir in the 1500m and Dina Asher-Smith at 200m.
Miller-Uibo finally claims world gold
Bahamas' double Olympic champion Shaunae Miller-Uibo finally claimed the world title that has eluded her in her five previous World Championships finals as she strode away with 400m gold in the women's race.
The 28-year-old came off the final bend well clear of the Dominican Republic's Marileidy Paulino and the rest of the field could not make any inroads into her lead.
Miller-Uibo won in a world leading 49.11 seconds, half a second clear of Paulino with Barbados' Sara Williams taking bronze.
Elsewhere, Great Britain's Olympic silver medallist Keely Hodgkinson put in composed performance to win her 800m semi-final in 1:58.51.
However American Olympic champion Athing Mu was fastest into the final, easing up en route to an impressive victory in 1:58.12.
Jemma Reekie, fourth in last summer's Olympic final, saw her World Championships campaign end at the semi-final stage after she finished fifth in a heat won by Kenyan contender Mary Moraa.
Hodgkinson, Mu and Moraa will vie for gold at 02:35 BST on Monday.
"I think Athing is going to be strong, she is a good competitor," said Hodgkinson.
"But I do not think that the gold medal is already on anyone's neck. There is a good five of us battling for the medal. So it is going to be very stormy race."
British relay teams advance to finals
Great Britain made their way into the 4x100m final safely and in style, with Asha Philip, Imani Lansiquot, Ashleigh Nelson and Daryll Neita winning their heat in 41.99 ahead of Jamaica.
Both teams will strengthen for the final at 03:30 BST on Sunday. Asher-Smith will come into the British quartet, while Shelly-Ann Fraser-Pryce, Shericka Jackson and Elaine Thompson-Herah, who completed a clean sweep of the 100m final earlier in the week, are likely to be brought into the Jamaican team.
The United States, with 100m finalists Melissa Jefferson and Aleia Hobbs in their team, qualified quickest in 41.56 seconds.
Great Britain's men's team, world champions in 2017, also qualified for the final, but are up against an impressive United States team, featuring Noah Lyles, Christian Coleman and Marvin Bracy.
The USA qualified fastest in 37.87, with Great Britain seventh fastest in 38.49.
