|Venue: Hayward Field, Eugene, Oregon Events: 15-24 July|
|Cover: Watch live on BBC TV, BBC iPlayer, BBC Sport website and mobile app (UK only)|
Seven-time American Olympic champion Allyson Felix bid farewell to a stellar career with a final World Championship medal, winning bronze in the 4x400m mixed relay in Oregon.
The Dominican Republic denied Felix a golden send-off while the Netherlands took the United States to silver.
Felix, 36, retires with 19 world medals, 13 of which are gold.
Elsewhere, on day one in Oregon, Britain’s Laura Muir and Katie Snowden made it to the 1500m semifinals.
Muir, who won Olympic silver in Tokyo last year, finished second in her run in four minutes and 7.53 seconds, while Snowden finished tenth in her run in four minutes and 6.92 seconds.
“The laps are always a bit nerve wracking, you want to think about the final but you have to get there first,” Muir told BBC Sport.
“It’s hard at this level, the strength at depth is really good.
“I knew there would be quite a few of us at the end, so I wanted to avoid hassle and save as much energy as possible.
“It felt good, it felt comfortable.”
The semi-finals take place on Saturday and the final on Monday.
Track and field great Felix announced earlier this year that this season would be her last, culminating in the World Championships – the largest track and field event hosted in the United States since the 1996 Atlanta Olympics.
USA took an early lead in Friday’s final with Elija Godwin in the first leg, while the home crowd cheered on Eugene Felix as she took the baton.
They slipped to third on the anchor leg as Dominican Republic’s Fiordaliza Cofil chased Kennedy Simon, who then failed to hold off a late charge from Dutch Femke Bol.
“It’s been amazing to watch Allyson over the years,” former US sprinter and four-time Olympic gold medalist Michael Johnson said on BBC television.
“I think the most impressive thing about her career is just the longevity.
“It’s very difficult to make the US team, even if it’s just one relay, and they’ve fielded five Olympic teams, eight World Cup teams and that’s unheard of.”
The quartet from Great Britain failed to reach the final after finishing fourth at the last edition of the World Cup in 2019.
Bradshaw ‘heartbroken’ after broken rod
Disappointing was Britain’s Olympic bronze medalist Holly Bradshaw, who had to drop out of the pole vault after an awkward landing when her pole broke while warming up.
The latest setback came after the 30-year-old missed the indoor season due to “various health, physical and mental challenges” after suffering from glandular fever in the winter.
It was the first time Bradshaw had had a pole snap in her career and she told BBC Sport it was a “very scary experience”.
“I wouldn’t be surprised if I tore my hamstring or my buttocks and I really hope I didn’t break my wrist because that was a long time ago,” she said.
“I’m heartbroken, this year has been one after another, I can’t even tell you how many things have gone wrong and that’s like icing on the cake. I almost have to laugh at it.”
Also for Great Britain, Nick Miller reached the men’s hammer throw final, but Scott Lincoln missed out on a place in the men’s shot put final.
In the men’s 100-meter dash, Zharnel Hughes reached the semifinals and finished second in his run with the fifth fastest overall time, but fourth place in his run was not enough for his compatriot Reece Prescod.
Hughes finished second behind American Fred Kerley, who stunned with a time of 9.79 seconds.
Also in the semifinals was Africa’s fastest man, Ferdinand Omanyala, who only landed in Eugene about three hours before his heat after visa problems.
The Kenyan was only allowed to enter the United States on Thursday and flew out of Kenya at 6:00 p.m. local time that night.
British athlete Chris Thompson will miss the marathon on Sunday due to delays in processing his US visa.
Organizers said Friday that less than 1% of athletes requiring visas have been denied papers to enter the United States or are still awaiting a response.
The first gold medal of the championships went to Peru’s Kimberley Garcia Leon in the women’s 20 km, who made history by becoming the first Peruvian to win a medal of any color at a World Athletics Championships.
“I’ve dreamed of this medal since I was little. I want to dedicate it to all Peruvians,” she said.
On the men’s side, Toshikazu Yamanishi from Japan defended his Doha 2019 title.