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

It is a strange concept for me. Is it the time to introduce this now? It's a bit odd.

Martyn Rooney on the anchor leg, can he hold on? No. GB still may qualify.

1. USA
2. Jamaica
3. Bahrain

GB still third as Emily Diamond takes the baton. Top three go through. USA and Jamaica are one and two.

All the teams have gone for the same configuration - male, female, female, male.

As the stagger unwinds GB are third.

Away we go! Rabah Yousif is off for Great Britain.

It looks like all the teams in the first heat are going with a male runner up first. That's a bit disappointing.

The top three in each heat qualify automatically.

South African long jumper Luvo Manyonga shot to fame two years ago after winning gold at the World Championships in London. He is an icon for South African youngsters and has also battled back from drug addiction to reach the top of his sport.

Here's how the British team will line up.

1. Rabah Yousif
2. Zoey Clark
3. Emily Diamond
4. Martyn Rooney

GB's Shelayna Oskan-Clarke after taking a tumble as she failed to qualify for the women's 800m final:

"I'm fine. I have no words, I don't know. Tactically it wasn't bad but could have been better. I just buckled over my legs. I don't know what happened there. I'm just not happy."

Shelayna Oskan-Clarke's legs just went...

I'm looking forward to this one - Great Britain are in the opening heat of this debut event, which will make its Olympics bow next summer. The USA and Jamaica ought to be strong.

Two men, two women per team. Do you go with your two men first? In the middle? Mix it up?

Deanna Price leads with 76.87m early on - Joanna Fiodorow of Poland has hit a PB with her first throw to challenge, 76.35!

No Brits. In the absence of injured four-time champion Anita Wlodarczyk, the battle for gold could be between three team-mates: Americans DeAnna Price, Brooke Andersen and Gwen Berry. They occupy the top three spots in this season’s world list – surely the USA will win a first World Championships medal in this event. The likeliest threat to US dominance is China’s Wang Zheng, the runner-up in London two years ago.

Stuart Eccles: These Doha Athletics championships should really make Fifa think about what they've done by awarding Qatar the WC. Its absolute nonsense, professional athletes should not have to contend with such inhospitable climates, no one wins

Tactical running from Eunice Sum, blocking out the inside line. Halimah Nakaayi pushes through and goes on to win - but that might be protested!

You can't do that. Sum takes second to qualify anyway.

Morgan Mitchell takes the third semi out.

World record holder Renaud Lavillenie will not be in the men's pole vault final - he fails to clear 5.70m.

There will be no British participation in the final then. Commonwealth champion Natoya Goule of Jamaica and Kenya’s 2013 world champion Eunice Sum are the standout names in the third semi.