Alison Dos Santos ended Karsten Warholm's reign as hurdles king at the world championships on Tuesday while Britain's Jake Wightman won his country's first 1500m gold in 39 years on a day of upsets.
Warholm may have been behind one of the most iconic moments in Olympic history when he smashed the 29-year-old world record to win the 400m hurdles at the Tokyo Games in a time of 45.94sec.
But the 26-year-old came to Eugene on the back of a hamstring injury which ultimately put paid to his medal attempt here.
Instead, Dos Santos ran the third fastest time of all time and a championship record of 46.29sec to win gold ahead of Americans Rai Benjamin and Trevor Bassitt.
"It's pretty awesome to win the world title on this track. I didn't care about the time because this is the first time I win a world title," said Dos Santos.
Warholm led coming into the home straight but seized up badly and eventually came in seventh (48.42), breaking a winning streak of 22 races, including 18 finals, dating back to September 2018.
"It was a very tough race," Warholm said. "I had an injury but to me it's always your fight and giving your all and leaving it all on the track.
"I felt I did that. I hope looking back I'll feel proud of that even though I prefer to take a medal."
Whilst everyone knew Warholm was coming back from injury, serious hopes were pinned on Olympic champion Jakob Ingebrigtsen in the men's 1500m.
But Wightman had not read the script, playing the Norwegian at his own game by kicking with 200 metres to run and holding his form through to the line.
Wightman sealed victory in 3min 29.23sec, Ingebrigtsen taking silver in 3:29.47, with Spaniard Mohamed Katir claiming bronze (3:29.90).
- Family affair -
In a bizarre twist, Wightman's father Geoff is in Eugene doing the in-stadium commentary.
Geoff, also his son's coach, was reduced to a cracked voice as he announced to Hayward Field: "That's my son and he's world champion."
"For him to be part of my journey to get to this point, and actually part of the the actual race itself is so unique," Wightman said of his father.
"I talked to him and he's very happy. I'm glad he showed some emotion."
Following on from Norway's Olympic gold medallists in failing to nail a world title was 2019 champion Daniel Stahl, the Swede eventually finishing fourth in the discus.
Australian Eleanor Patterson won high jump gold in the fourth final of the night with 2.02m on countback from Ukraine's Yaroslava Mahuchikh, Italian Elena Vallortigara taking bronze.
"I'm honestly speechless right now," Patterson said afterwards. "I'm already starting to get sore cheeks from smiling."
- Kerley out of 200m -
Day five of action at the world champs also saw newly-crowned 100m champion Fred Kerley fail to advance from the semi-finals of the 200m.
Kerley set off smoothly from the blocks but was left grimacing as he hit the home straight at Eugene's Hayward Field, eventually finishing sixth in 20.68 seconds.
Kerley later said he had cramped up in the later stages of the race, but insisted he would be fit to race in the relays.
"Bit of cramp, but it's all good," Kerley said. "I'm not in pain, I'll be good."
While Kerley was left digesting a disappointing early exit, there were no such worries for defending 200m world champion Noah Lyles, who romped home in his semi-final with a blistering 19.62sec.
The main threat to Lyles' hopes of retaining his 200m world title may well come from teenage team-mate and emerging rival Erriyon Knighton. The 18-year-old prodigy blazed home to win his semi-final in 19.77sec.
In the women's 200m, Shelly-Ann Fraser-Pryce kept her bid for a sprint double on track as she sailed into the final.
Fresh from winning a record fifth world 100m title, Fraser-Pryce timed a season's best of 21.83 seconds in the third of three semi-finals.
Joining the 35-year-old, a world 200m champion in 2013, in Thursday's final will be her two teammates who helped snatch an unprecedented cleansweep of the 100m podium for Jamaica on Sunday, Shericka Jackson and Elaine Thompson-Herah.
Alongside the trio of Jamaicans in the final will be Britain's Dina Asher-Smith, the reigning world 200m champion who was fourth in the 100m, Americans Abby Steiner and Tamara Clark, Niger's Aminatou Seyni and Switzerland's Mujinga Kambundji.