Six athletes are pulling clear at the front.

Britain's Katie Snowden is also among them.

Muir, Kipyegon and Hassan are in a trio across the front at the bell...

Sifan Hassan has moved up behind world record holder Kipyegon.

Laura Muir is coming around the outside too.

Two laps to go.

Laura Muir and Sifan Hassan are side by side at the back early on with this semi-final being run at a higher pace than the last.

Faith Kipyegon, meanwhile, is lurking near the front.

The top six go through, remember. Britain's Katie Snowdon is in this race too.

Off they go on the track in this stacked semi-final.

Sifan Hassan has plasters all over her leg after her fall last night...

There was no such joy for defending champion Fred Kerley, however...

And quickly, just before we see Faith Kipyegon, Laura Muir and Sifan Hassan, tussle it out, here's how Zharnel Hughes recovered to reach tonight's men's 100m final.

Birke Haylom, Ireland's Ciara Mageean, Cory Ann McGee and Ludovica Cavalli are the others through.

Great Britain's Melissa Courtney-Bryant has done it!

It was a bit of a dash for the line but she's made it to the world 1500m final with a fifth-placed finish.

Nelly Chepchirchir of Kenya won that one impressively in the end.

Melissa Courtney-Bryant is at the back but well within touch with a lap to go.

Ethiopia’s 17-year-old world Under-20 champion Birke Haylom and compatriot Hirut Meshesha will be in the mix.

Australia's Linden Hall is on the front.

They're off in this first women's 1500m semi-final.

Great Britain's Melissa Courtney-Bryant needs to finish in the top six to go through.

Michael Johnson
Four-time Olympic gold medallist athlete on BBC TV

Technically everything is good, but it's like Hughes can't generate enough power to push through. It's like he's not getting that foot down and planting it.

Denise Lewis
Olympic heptathlon gold medallist on BBC TV

Hughes has to react better with the calibre of the field he is in. We know he was the pedigree, but it's just a little bit too much.

Harry Poole
BBC Sport in Budapest

Goodness me, a significant upset in that last men's semi-final

The reigning champion Fred Kerley is OUT.

He wasn't hanging around either after seeing confirmation of that result on the screen, initially refusing to turn around as he headed out of the stadium, but he's back now to do his media duties. That will be a sore one for him to take.

The door to the men's 100m medals were already wide open and Britain's Zharnel Hughes is bang in contention. You do not want to miss that final!

Image source, Getty Images

Next on track is the women's 1500m semi-finals. There are two races with the top six from each going through.

Great Britain's Melissa Courtney-Bryant is in the first semi but otherwise all of the big names are in a stacked second.

It features Laura Muir, world record holder Faith Kipyegon and 2019 champion Sifan Hassan, who had that extraordinary tumble in the 10,000m final last night.

Britain's Katie Snowdon is in there too.

After all of that, Britain's Zharnel Hughes was the fourth-fastest in those semi-finals. Fix the start and he's in with a chance.

Noah Lyles, the quickest with 9.87 seconds, looks the man to beat, however.

Dame Jessica Ennis-Hill
London 2012 Olympic heptathlon champion on BBC TV

It's a huge blow. We were all sat in the studio completely shocked. This is what happens at championships. Huge shock, but that's what happens unfortunately.

Image source, Getty Images

Michael Johnson
Four-time Olympic gold medallist athlete on BBC TV

Fred Kerley hasn't looked dominant all year. He would've walked through the park with this if he was ready. That is a big blow for him as defending world champion.

Letsile Tebogo of Botswana finished a surprise second in that semi-final.

The BBC TV team are stunned at Kerley's exit. Me too.

Fred Kerley is walking away from the track already, despite an official trying to get him to stay.

His time of 10.02 is not going to be enough.

Ferdinand Omanyala goes through as the fastest loser instead.