Bahrain's Salwa Eid Naser destroyed the field and stunned Olympic champion Shaunae Miller-Uibo as she became the first Asian to win the women's 400 metres World title on Thursday.
The Nigerian-born Eid Naser, 21, surged past Miller-Uibo on the back straight to win in 48.14 seconds, the third fastest time in history.
Miller-Uibo took silver in 48.37. The Bahamian suffered her first defeat over the distance since she inexplicably stumbled with victory in her grasp in London two years ago.
After running the fastest 400 metres since 1985, Eid Naser seemed to be in a state of shock as she sat on the track and covered her mouth with her hand at the end of the race.
"I still can't believe the time. Crossing the line and seeing the time, I went completely crazy," she told reporters. "I screamed so loud, I was so happy. I am used to chasing and today I wanted to be chased and it worked."
Miller-Uibo managed to close the gap down the back straight but left it too late to catch her rival, despite herself running the sixth-fastest time in history.
Jamaica's Shericka Jackson took bronze, while defending champion Phyllis Francis also ran a personal best of 49.61 but could still only manage fifth.
Miller-Uibo was clear with less than 20 metres left two years ago in London but she tripped on her own foot, stumbling almost to a standstill as her rivals stormed past.
The 25-year-old also won silver at the world championships in Beijing four years ago and bronze in the 200 metres in London.
A few jeers were heard as Eid Naser's name was announced at the start, with Bahrain being one of the countries to have boycotted Qatar because it accuses the Gulf state of supporting terrorism. Qatar denies the allegation.
The stadium was nearly full at one point in the evening but many athletics fans had left before the race, which started just before midnight.
The runners were greeted with the light show that has been a feature of the championships, although there was also shouting and whistling as the runners waited for the starting gun.
Naser produced a stunning burst of pace as she caught the big-striding Miller-Uibo and then powered home.
"I don't think I would have done that alone, Miller-Uibo pushed me, she's really competitive," added Eid Naser. "Without her I don't think I would have gone this fast."
Germany's Kaul wins thrilling decathlon battle
Germany's Niklas Kaul survived a gruelling battle to win the World Championships decathlon gold after the event was blown wide open by the withdrawal of injured defending champion Kevin Mayer.
Even with French World record holder Mayer out of the way with a hamstring problem, it was far from smooth sailing for Kaul on a rollercoaster day that saw a different name at the top the leaderboard after each of the five events.
But it was the 21-year-old Kaul who stood on top of the podium at the end after winning the final event, the 1,500 metres, to record a score of 8,691 points and become the youngest ever world decathlon champion.
"I cannot really describe the feeling," said Kaul. "I have no idea how it happened. I am not the best decathlete who competed here.
"I don’t think I’m the favourite for (next year's) Tokyo (Olympics) because Kevin (Mayer) did 9,100 points ... and is still the best decathlete there is in the world."
Estonia's Maicel Uibo took silver with 8,604, just as his wife Shaunae Miller-Uibo of the Bahamas did an hour earlier in the 400 metres.
Gold continued to elude Canada's Damian Warner, who had to settle for third on 8,529. It was a disappointing end for Warner considering his trophy cabinet is already full of bronze and silver medals, including third place at the Rio Olympics and second and third finishes at the Worlds.
Kaul had not figured in the medal discussion through the opening eight events then shot into contention with an astonishing throw of 79.05 metres in the javelin that brought a gasp from the largest crowd yet at the Khalifa Stadium.
The effort, almost seven metres more than the next best, vaulted him up to third.
With only 19 points separating the top three, it was all to play for going into the final event - the 1,500m.
With the clock now well past midnight, the group of weary decathletes stepped up to the line in a now nearly empty stadium with Warner, starting 15 points back of leader Uibo, racing to the front and leading through the opening lap.
But the Canadian could not maintain the pace as Kaul seized his chance and charged into the lead, powering home in a time of four minutes, 15.70 seconds. He was almost seven seconds clear of countryman Tom Nowak and more than 15 seconds ahead of a fading Uibo.
Johnson-Thompson captures Britain's second gold
Katarina Johnson-Thompson clinched gold in the heptathlon with the year's best performance after holding off the challenge of defending champion Nafissatou Thiam on Thursday to give Britain their second title at this year's world championships.
The 26-year-old Johnson-Thompson finished 304 points ahead of the Belgian, who was on a three-year winning streak in the event, with Verena Preiner of Austria claiming bronze.
Having taken the lead on the first day of competition, Johnson-Thompson extended her advantage with a long jump of 6.77 metres - the best ever recorded in a women's heptathlon - to take a 216-point lead over Thiam.
The Belgian, had briefly reclaimed the lead on the first day after the shot put but was dislodged from top spot when Johnson-Thompson ran a season's best 23.08 seconds in the 200 metres.
After a personal best javelin throw of 43.93 metres, Johnson-Thompson entered the final event, the 800m, with a 137-point lead over Thiam.
She secured gold with a run of 2 minutes 07.26 seconds, lifting her points tally to a world leading 6,981 and breaking the British record set by Jessica Ennis-Hill when she won gold at the 2012 London Olympics.
"These whole two days have been so fast and because it has been at night it's actually felt like a dream," Johnson-Thompson told the BBC.
"I've just tried to compete, I've just tried to perform. I've just tried to beat myself. And I think I found a formula that works. I just want more."
Johnson-Thompson fell short of the 7,000-point mark, something she says is one of her main career goals, but finished with the sixth-best heptathlon points haul of all time.
The 25-year-old Thiam, who walked away from her third attempt in the javelin, finished the 800m in 2:18.93, finishing 304 points behind Johnson-Thompson.
Johnson-Thompson said of her Belgian rival: "I witnessed her making 7,000 points and showing that it is doable and also a requirement in order to win. She's raised the bar and I'm glad I'm able to follow and step up."
Dina Asher-Smith had won the 200 metres on Wednesday to become the first British woman to claim a global sprint title.
China's Gong retains shot put title by 8cm
China's Gong Lijiao retained her World shot put title but got a fright when Jamaica's Danniel Thomas-Dodd nearly pipped her to gold with her last attempt.
Gong, who has won 13 of her 14 competitions this season, led from the first round with a throw of 19.07 metres, bettered that with 19.42 on her second and then managed 19.55 with her fourth.
She had an anxious moment, however, when Thomas-Dodd threw a personal best of 19.47 metres, missing out by eight centimetres.
Germany's Christine Schwanitz, who has taken time away from competing and had a child since she won the world title in 2015, claimed the bronze with 19.17.
Husband-wife each win silver
Estonian decathlete Maicel Uibo and his wife, Bahamian runner Shaunae Miller-Uibo, had two reasons to celebrate after they each won a silver medal at the World Athletics Championships on Thursday.
"Both medals at the same time, on the same night," Uibo told reporters after his final event. "It's double the joy."
Miller-Uibo, the 2016 Olympic gold medallist who had been favourite to win the 400 metres World title in Doha, finished second after Salwa Eid Naser of Bahrain stunned her by running the third fastest time in the event's history.
As Miller-Uibo crossed the finish line, her husband was preparing to run the 1,500 metres, the tenth and final event in the decathlon. He came in third, giving him the overall silver medal.
Uibo said his race preparations had prevented him from watching his wife's race, but he was still keeping a close eye on the results.
"I was only able to refresh the results page as I was getting ready for my 1,500 metres," the 26-year-old said.
"I've got to watch the real race in the replay later on."
Miller-Uibo then hung around the track by the finish line to watch her husband race.
"He was hoping for the gold," the 25-year-old told reporters separately after her event. "I knew he wasn't quite that well in shape for his 1,500 metres, but he gave it his all. I'm so proud of him."
The couple, who had dominated their disciplines in the lead up to the Doha championships, took a joint walk along the track in the Khalifa International Stadium with their respective flags draped around their shoulders.
"As athletes we're very competitive," Uibo said. "We train together, we practice at the same time sometimes. It's always a little bit competitive on the track and off the track."
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