USA almost drop the baton!

A nightmare exchange between the second and third legs, it means the overwhelming favourites have work to do.

The top three in each heat, plus the other two fastest teams, qualify for tomorrow's final.

South Africa, who have the world leading time this year, are the leaders after the first leg.

Through the second round in the javelin and Ireland's Kate O'Connor still leads in this event.

Jade O'Dowda and Katarina Johnson-Thompson are 14th and 16th respectively.

Competition leader Anna Hall gets the third and final round going with a personal best throw of 48.13m, moving from sixth to fourth.

The American team are the ones to watch in this first heat.

Christopher Bailey, Demarius Smith, Bryce Deadmon and Jenoah McKiver are the runners here - but they have plenty of talent to come in for the final, including 400m hurdles champion Rai Benjamin.

Great Britain won Olympic bronze last year but even making the final here could be tough because of injuries.

Toby Harries was part of the mixed 4x400m team who missed out on a medal last weekend, and runs in the heats for GB here alongside Seamus Derbyshire, Charlie Dobson and Lee Thompson.

Matthew Hudson-Smith could come in for the final if GB get that far after missing out on the individual medal race, but he and Dobson have been dealing with fitness issues.

GB go in heat two, while USA - the Olympic champions who have won this world title in nine of the past 10 attempts - are in heat one.

We'll keep you updated on the multi-event sports this morning - but the first of the relay heats are about to get under way.

These have been a fruitful source of medals for GB in recent years, so let's see if that proves true in Tokyo too...

Image source, Getty Images

World Athletics has defended the location of the warm-up track for the Tokyo championships after some competitors criticised its distance from the stadium.

Yoyogi Park is a two-and-half-kilometre drive from Japan National Stadium, and requires a bus journey understood to take about 15 minutes on average, with athletes needing to leave between 50 minutes to an hour before their event.

Great Britain's Keely Hodgkinson is among those to have commented on the pre-event logistics.

"I think the whole warm-up situation, you're warming up for almost two hours," said the Olympic champion after Friday's 800m semi-final.

"It can be quite draining, so maybe we will have to look at doing something better come Sunday."

The warm-up track installed for the Tokyo 2020 Olympics, which was located next to the stadium, was dismantled after the Games.

A World Athletics statement read: "The athlete experience is of utmost importance for World Athletics. We have put a lot of consideration into their preparations within the constraints of locations and venues.

"This type of configuration is not unique - as we have seen from previous Olympic Games and other major athletics championships."

Stef Reid
British para-athlete & Paralympic bronze medallist on BBC TV

KJT has done so well to be working on the events. We normally know her as a high jumper and a long jumper. 40.51 there so an improvement and some valuable points. She's done so well to lift the ceiling in all the other events and the javelin and the 800m are two examples of that.

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A statement from British Athletics on X: "Unfortunately Abi Pawlett has withdrawn from the heptathlon as she is still suffering the after-effects of yesterday's fall in the hurdles. We wish Abi a speedy recovery."

There has been a major upset in the decathlon, where Switzerland's former world indoor champion Simon Ehammer has failed to register any points in the high jump.

Ehammer, who finished fourth at Paris 2024, failed three times at his opening height of 1.93m, meaning he will get no points in this discipline - effectively ending his medal chances.

USA's Kyle Garland is currently still in gold medal position.

Image source, Getty Images

A throw of 40.51m from Katarina Johnson-Thompson with her second attempt.

An improvement on her first throw of 38.82m, but not enough to pull her significantly up the field.

We're through the first round of the javelin, and Ireland's Kate O'Connor leads in this event with a personal best of 53.06m.

Competition leader Anna Hall is in sixth, while Great Britain's Jade O'Dowda and Katarina Johnson-Thompson are 11th and 13th respectively.

There are 20 athletes in the field with Nafi Thiam and Great Britain's Abigail Pawlett not starting.

Harry Poole
BBC Sport in Tokyo

It certainly looks like Anna Hall is on her way to heptathlon gold.

Hall's javelin best of 47.32m is worth 808 points, while her 800m best of 2:01.23 equates to 1097 points - which would give her a final total of 6,946.

Johnson-Thompson's javelin best of 46.14m (785 points) and 800m best of 2:04.90 (1041) would put her on 6,700 points.

Ireland's Kate O'Connor, meanwhile, has an excellent javelin best of 52.92m but her 800m time of 2:10.46 does not quite measure up. Worth 917 and 958 points respectively, she'd be on 6,699.

So, it could be quite the battle for silver!

Taliyah Brooks, currently in second, will need to out-do her personal best performances to challenge.

Team GB's Amy Hunt speaking to BBC Sport after winning her 200m silver medal yesterday about if she would ever do 400m: "I would but people need to give me 24 hours to let me live in the 200m for a bit. The way I finish my 200m everyone's like 'you have so much strength'. It's definitely part of the plan that we'll start to weave into the future but I'm enjoying being a proper sprinter."

Image source, Getty Images

Time for the sixth event in the heptathlon - it's the javelin.

Katarina Johnson-Thompson throws 38.82m with her first of three attempts, while team-mate Jade O'Dowda manages 40.40m.

Kate O'Connor, in medal contention for Ireland, throws 53.06, a personal best and almost 10m further than anyone else who has thrown so far.

Ask Me Anything

Heptathlon is a combination of track and field events, consisting of seven disciplines across a two-day period. It is often considered to be the ultimate all-round test for female athletes.

The events athletes must participate in for the heptathlon are:

• 100m hurdles: Athletes sprint over 10 hurdles along a 100m track. Hurdles are set 8.5m apart
• High jump: Athletes jump over a high horizontal bar. They aim to clear the highest height without the bar dropping
• Shot put: Athletes throw a heavy ball, called the 'shot', as far as possible. The shot weighs 4kg for heptathlon events
• 200m: Athletes run a distance of 200m, which is a half-lap of the track
• Long jump: Athletes sprint down a runway and jump into a sandpit
• Javelin throw: Athletes throw the javelin as far as possible
• 800m: The final event is an 800m run, which requires athletes to complete two laps of the track in the fastest time

Day one consists of the 100m hurdles, high jump, shot put and 200m. Day two is the long jump, javelin throw and 800m.

Dame Jessica Ennis-Hill
Three-time world heptathlon champion on BBC TV

It's so sad to see but for us she's [Nafi Thiam] a true champion. She is a three-time Olympic gold medallist. I remember seeing her in 2016 in Rio where she beat me. I was like she's phenomenal. It's so hard to keep performing like that.

Dame Jessica Ennis-Hill
Three-time world heptathlon champion on BBC TV

[Katarina Johnson-Thompson] has got two more events left and she's currently in bronze medal position. She's got a solid javelin and then she's coming into the 800m and she's strong across that distance. I think she's rivalling for a silver but there is Kate O'Connor there as well.