A new-look Great Britain quartet won 4x100m bronze in the final race of the day nine of the World Championships.
With Jona Efoloko, 22, preferred to Adam Gemili on the opening leg and Reece Prescod on the anchor, Britain held off Jamaica to ensure a medal.
Canada exploited a slack final changeover from the United States to take gold ahead of their neighbour.
A mystery leg injury to Dina Asher-Smith cost Great Britain’s women a shot at a medal in the 4x100m relay.
The 26-year-old, who finished fourth in the 100m and won bronze over 200m during a hectic schedule in Oregon, hobbled through the final 15m of her third leg.
Great Britain, who had been third in the race, slipped back to eighth as she slowed. Daryll Neita ran the fastest split of anyone in the race – 9.57 seconds – on the anchor leg, but it was only enough to regain sixth.
“I feel confused because I felt fine coming in, but when I was going round the bend my legs just stopped corresponding with me,” Asher-Smith told BBC Sport.
“I hope it is nothing serious as I have a lot more races to do this year. I feel awful because we were running well.”
Asher-Smith has been named in the England team for the Commonwealth Games, which begins next week, and has three titles to defend at August’s European Championships in Munich.
At the front of the race, the United States claimed a memorable victory over an all-star Jamaican team.
Shelly-Ann Fraser-Pryce, Shericka Jackson and Elaine Thompson-Herah, who filled the podium in the 100m, were part of the Jamaica quartet attempting to defend their 2019 title.
But excellent legs from Melissa Jefferson and Abby Steiner gave the Americans an advantage that survived Jackson’s surge for the line by four hundredths of a second.
Germany took bronze.
‘We are serial medallists’
Great Britain’s men narrowly lost out to Italy in the Tokyo Olympic final last summer, before being stripped of silver following CJ Ujah’s positive test for a banned substance. Prior to that the team had won silver at Doha 2019 and gold at London 2017.
With Richard Kilty injured and Gemili out of form, it opened up vacancies. Efoloko, a former world junior 200m champion, took his chance with a solid opening leg before mainstays Zharnel Hughes and Nethaneel Mitchell-Blake moved away from the pack and Prescod, who has struggled for fitness and focus in recent years, came home hard.
“We have shown we are serial medallists in the relay,” said Mitchell-Blake, who is captain of the British team in Eugene.
“It is testament to our individual skills and collective efforts.
“Ultimately the aim is to come away from the next world championships with a gold and then go onto Paris 2024. It is a stepping stone, we will get better because we have to raise our game.”
The final race of the day did not end with the expected home team victory as Elijah Hall’s clumsy handover to Marvin Bracy opened the door for Canada’s 200m Olympic champion Andre de Grasse to snatch gold.
Eilish McColgan, whose preparations have been blighted by a hamstring niggle, finished 11th in the 5000m final, two places ahead of fellow Briton Jessica Judd.
Gudaf Tsegay took gold ahead of Kenya’s Beatrice Chebet and fellow Ethiopian Dawit Sayaum, with world record-holder Letesenbet Gidey fifth and Olympic champion Sifan Hassan sixth.
“That was tough. It took all my will in that last kilometre to keep going and not drop out,” said McColgan.
“Honestly the pace of those top girls is just insane. I did what I could but there was nothing more there for me.
“It has been a tough championships for me all round, but I am still proud. I made two finals.”
Emmanuel Korir came good on the big stage once again in the 800m, adding the world title to the Olympic gold he won last summer. The Kenyan reeled in Canada’s Marco Arop coming into the home straight to take gold ahead of Algeria’s Djamel Sedjati.
Korir’s winning time of 1:43.71 is still short of the world-leading time run by Britain’s Max Burgin last month. Burgin pulled out of the event before the first round after developing a deep vein thrombosis.
Felix returns on a wing and a plea
Great Britain’s 4x400m relay team of Ama Pipi, Laviai Nielsen, Victoria Ohuruogu and Nicole Yeargin, secured their place in the final with a solid second place behind the United States in their heat.
Allyson Felix, who was thought to have run her last competitive race after helping the USA to bronze in the mixed relay earlier in the week, ran in the American quartet after being called in at late notice.
“I was diving into some hot wings and a root beer float, but I got a phone call and they asked if I was willing to come back and help the team get a position, so I dropped the wing!,” said the 19-time world medallist.
The United States team could be strengthened with the likes of 400m hurdles champion Sydney McLaughlin and Olympic 800m champion Athing Mu before the final at 03:50 BST on Monday.
Earlier in the day, Great Britain’s Lorraine Ugen and Jazmin Sawyers reached the long jump final at the World Championships in Eugene.
The pair each jumped 6.68m to finish in the top 12 after missing the automatic mark of 6.75m.
Ugen, 30, and Sawyers, 28, will compete in Sunday’s final on the last day of the Championships.
“I’m happy – the job in qualifying is to make it to the final,” said Sawyers, who recorded a season’s best.
“There’s definitely some technical things I can do better, but that’s my first world final at my third try so I’m really happy.
“I don’t know why I can’t do it in round one and just get the auto-Q but you know what? I just said before, people pay for tickets, I’ve got to give them a full three rounds of entertainment, I did it for them.”