|2019 World Athletics Championships|
|Venue: Khalifa International Stadium, Doha Dates: 27 September-6 October|
|Coverage: Watch live on BBC TV, BBC iPlayer and BBC Sport website and app; Listen live on BBC Radio 5 Live; Live streams, clips and text commentary online.|
Dina Asher-Smith’s hopes of a third 2019 World Championships medal remained intact as both Britain’s 4x100m relay teams qualified for Saturday’s finals.
Britain’s men, the defending champions, made it through their heat with a world lead time of 37.56 seconds in Doha.
Britons Neil Gourley, Josh Kerr and Jake Wightman looked in good shape as they reached Sunday’s 1500m final.
USA’s Dalilah Muhammad set a world record for the second time this year as she won the women’s 400m hurdles final.
Asher-Smith, the 200m champion and 100m silver medallist, will be brought into the quartet for the final after sitting out Friday’s heat.
She relied on Asha Philip, Imani-Lara Lansiquot, Ashleigh Nelson and Daryll Neita and they kept their composure to bring the baton safely around in a season’s best time of 42.25 seconds.
At the World Relays earlier in the year, Nelson was involved in a baton-exchange error, but her exchange with Neita, on the anchor leg, was faultless.
Neita told BBC Sport: «We’ve practised so hard. We’ve had an amazing camp coming into this. I feel like we’re moving away from the technical side and moving in to the trust.
«We all trust each other. I’m really proud of us and Saturday is going to be great.»
Jamaica’s quartet, which included 100m gold medallist Shelly-Ann Fraser-Pryce, won the heat in 42.11.
Defending champions USA won their heat to take their place in the final.
The British men’s team of Adam Gemili, Zharnel Hughes, Richard Kilty and Nethaneel Mitchell-Blake were also impressive as they won their race with clear distance between themselves and the Americans, who included 100m champion Christian Coleman and came third with Brazil second.
Gemili, fourth in the men’s 200m, told BBC Sport: «I’m actually good. I feel really fresh. It’s always an honour to come out with these guys. We were looking for redemption, especially myself and Zharnel, after what happened in the individuals.»
Great Britain captain Kilty added: «We knew the key to this was relaxation. I said to the lads at the start – this is one seamless effort of taking the baton round, and we’ve done that nicely We’re full of confidence, relaxed and ready to go again.»
Mitchell-Blake said: «Right now we’ve got to rewrite the history books and focus at what’s on hand right now.»
Muhammad sets second world record in a year
In the women’s 400m hurdles, Muhammad held off compatriot Sydney McLaughlin in a thrilling final.
The 29-year-old won in 52.16 seconds – 0.04 faster than the time she set in July.
McLaughlin, 20, produced a brilliant late sprint to clock 52.23, which is the third fastest ever.
Jamaica’s Rushell Clayton took bronze in 53.74.