Great Britain faced setbacks that saw them fall short but still managed to qualify in both the men’s 4x400m and women’s 4x100m.

On the penultimate day of the World Athletics Championships, the men’s and women’s relay events got underway, bringing with them all the usual intensity and a fair share of mishaps.

Several strong teams struggled with baton exchanges, including dropped handovers and disqualifications that reshaped the finals line-up.

Men's 4x400m

In a dramatic turn of events in the men’s 4x400m relay heats, reigning Olympic champions USA looked to have made an early exit but have been given a second chance in the form of a morning "run-off" with Kenya for a place in the final.

The American squad, who set an Olympic record of 2:54.53 en route to gold in Paris, had difficulty during the third-leg handover, almost colliding with Zambia during the changeover.

The mishap proved costly, as the defending champions crossed the line in 3:01.06, only sixth in their heat, and it appeared they had failed to qualify either automatically or as one of the fastest non-automatic qualifiers.

However, officials ruled that both the USA and Kenya "were seriously impeded by Zambia, resulting in both teams missing the opportunity to qualify for the final.

"Following the disqualification of Zambia, the Referee has decided to offer both USA and Kenya the opportunity to race for lane one in the final, in addition to the eight already qualified teams."

The nations must field exactly the same line-ups and will race again, from their same heat lanes of four and seven, at 10.40am Japanese time.

Meanwhile, South Africa dominated the same heat with a commanding lead, posting a time of 2:58.81 to comfortably secure victory. Qatar followed with a strong performance of their own, setting a new national record at 3:00.15 to claim second place. The Netherlands rounded out the automatic qualifiers from that heat, clocking 3:00.23.

In the second heat, Botswana delivered a standout performance, surging to victory in 2:57.68 with Olympic 200m champion Letsile Tebogo running the third leg. Belgium also impressed, finishing close behind in 2:57.98.

Australia initially crossed the line in third, but their result was later disqualified due to a baton exchange outside the legal take-over zone. Their disqualification paved the way for Great Britain to move into the third automatic qualifying spot. The British quartet of Lee Thompson, Toby Harries, Seamus Derbyshire, and Charlie Dobson clocked 2:58.11 to advance to the final.

The fastest non-automatic qualifiers were Jamaica in 2:59.13 and Portugal in a national record in 2:59.70.

Women's 4x400m

It was disappointment for Great Britain in the women’s 4x400m as on paper, they entered their heat as the second fastest but ended up finishing in last place with the quartet of Victoria Ohuruogu, Poppy Malik, Nicole Yeargin and Yemi Mary-John running 3:25.84.

In that same heat Jamaica set a world lead of 3:22.77, with Nikisha Pryce producing a great anchor leg.

Norway set a national record of 3:23.84 to finish in second place and Poland rounded out the automatic qualifiers in that heat as they clocked 3:24.39.

In the other heat it was the reigning world champions, USA, who created a huge lead by almost 50m as they finished well ahead of the rest of the field, running 3:22.53. Belgium were second in 3:23.96 and Netherlands rounded it out with 3:34.03 - with the absence of newly crowned 400m hurdles champion Femke Bol.

France (3:24.33) and Italy (3:24.71) were the two non-automatic qualifiers, advancing to the final.

Men's 4x100m

The men’s 4x100m relay final delivered high drama and heartbreak, with pre-race favourites Jamaica suffering a devastating baton drop that dashed their hopes of gold.

With momentum behind them after Oblique Seville's 100m title and Kishane Thompson’s silver, Jamaica looked poised to dominate. Their relay team was in strong contention as Oblique Seville smoothly handed the baton to Ryiem Forde for the third leg. However, disaster struck on the final exchange.

A miscommunication between Forde and anchor leg runner Thompson led to a fumbled hand-off, with the baton dropping to the floor.

Canada capitalised on the chaos. Anchored by Olympic veteran Andre De Grasse, they stormed to victory in 37.85, holding off a fast-finishing United States team who clocked 37.98. Germany claimed the bronze medal with a strong run of 38.12.

Great Britain also endured relay heartbreak. Their squad appeared in good form until the final exchange, when anchor Eugene Amo-Dadzie mistimed his take-off and ran out of reach for Jona Efoloko, leading to a failed handover.

Amo-Dadzie said: "I think, in a relay, it's a team effort, right? But each individual has a lot to do. I guess it's a natural disappointment.

"When we're in a situation where you feel like you didn't do the job to the best of your ability, because it doesn't just impact yourself, it impacts the whole team. So I think that's probably one of the main frustrations, and I appreciate the grace that's being shown by my teammates - that's very much appreciated.

"Practice has been great. We're not just saying that truly. And the simple direction was to go out there and do the same thing ultimately. So yeah, that's really frustrating. We 100% will be back from it."

South Africa will be given a solo rerun in the men’s 4x100m relay after their heat was disrupted by a collision with Italy during the first changeover.

The incident, which occurred in heat two, prevented the South African quartet from completing the race. Following a review, organisers have confirmed the team will be allowed an additional opportunity to qualify for the final.

The rerun is scheduled for Sunday morning at 10:33am local time, with South Africa set to run alone in lane six. The same four athletes from the original heat must compete, in the same running order.

To advance, they must beat 38.34 - the time posted by the eighth-fastest team in the heats. If successful, they will be added to the final as a ninth team and placed in lane one. The inclusion of South Africa will not impact the qualification of the existing eight finalists.

In the second semi-final, Ghana emerged as the surprise stars, powering to a national record of 37.79 to top the standings. The Netherlands followed with 37.95, while host nation Japan delighted the home crowd by finishing third in 38.07.

Women's 4x100m

Jamaica found redemption in the women’s 4x100m relay heats after the heartbreak in the men’s event, powering to a convincing victory in their heat with a time of 41.80. The performance restored hope for the sprinting powerhouse as they booked their spot in the final with ease.

Spain finished a distant second in 42.53, followed by France, who claimed the third automatic qualifying spot in 42.71.

In the other heat, the United States laid down a marker with a commanding performance, clocking a world-leading 41.60. Their speed and cohesion made them clear favourites heading into the final.

Germany followed closely in 41.86, while Great Britain’s team, featuring Dina Asher-Smith, Success Eduan, Desiree Henry and Daryll Neita, looked sharp and composed. Despite being narrowly edged out by Germany, they posted a strong 41.88 to safely secure qualification.

Elsewhere, Canada delivered a national record of 42.38 to advance, while Poland claimed the final qualifying spot in 42.83.