Light show complete. Let's get this penultimate final under way.

On your marks, set, BANG.

Steve Cram
BBC Sport athletics commentator in Doha

This looks like a very strong Jamaica team.

USA and Jamaica look good but Great Britain were almost a second quicker than Poland in qualification, and both sides have changed their line-ups. What difference will Emily Diamond make?

Olympic silver medallists Jamaica impressed in winning Saturday’s first heat and will be desperate to bounce back, having missed out on a medal at London 2017 when second leg runner Anneisha McLaughlin-Whilby suffered an injury.

USA’s 4x400m women have won the last six Olympic golds, and five of the last six world titles. Mixed relay gold medallist Allyson Felix ran in the heats for the USA but will not run in the final. Dalilah Muhammad, who won the 400m hurdles title in Doha, will run the third leg.

Watch out too for Poland, who won bronze two years ago.

Back to the women's 4x400m and Clark, Nielsen and Diamond were members of the British team who won silver in this event two years ago in London.

GB have won a medal in this event in seven successive World Championships.

Can they finish on the podium again?

Coming up very shortly is the women's 4x400m relay final and here's how Great Britain will line up.

Emily Diamond comes in on the third leg for Jessica Turner, who ran in the heats.

Image source, BBC Sport

Estonia's world leader Magnus Kirt has seriously hurt himself in the javelin final. He's leaving on a stretcher after hurting his throwing shoulder.

He's in silver medal position at the moment but won't be able to throw again.

Anderson Peters still leads going into the final round.

Image source, AFP

Nia Ali is off on her lap of honour with two very special guests.

In her arms is Yuri, her 13-month-old daughter, and the natural in front of the camera is four-year-old Titus.

SO cute.

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

That is certainly a step in the right direction and a huge sigh of relief for Keni Harrison.

Danielle Williams was all over the place from the very beginning.

BBC Sport

Women's 100m hurdles silver medallist Keni Harrison: "I want to run the best I can. I'm so glad another American was able to go out there and get the win.

"I'm so happy to get my first medal. The Americans are always tough. I knew we were both going to give our best and represent Team USA."

Grenada's Anderson Peters has extended his lead to 86.89m.

Oh, Danielle Williams is fading here...

Danielle Williams is sandwiched inbetween Keni Harrison and Nia Ali.

Everyone is cleanly away...

Right, this should be a belter.

The semi-finals earlier today were quick. Danielle Williams, Keni Harrison, Tobi Amusan, Nia Ali and Janeek Brown will be, you suspect, duking it out for the medals.

• 18:50 BST - Women's 100m hurdles final
• 19:15 - Women's 4x400m relay final
• 19:30 - Men's 4x400m relay final

Lee Gibson: Is throwing yourself on the floor after throwing actually a part of javelin technique these days?

Steve Backley referred to it as a swan dive earlier. I think it looks more like they're trying to do the worm. Apparently it gives some athletes that extra bit of oomph, but it just looks painful...

Image source, Reuters

At the cut off in the javelin final, it's Grenada's Anderson Peters who leads with his 86.69m first effort with Magnus Kirt and Johannes Vetter second and third respectively at the moment.

The top eight progressing to the second part of this final all threw over 80m.

But London 2012 Olympic champion Keshorn Walcott is out of the competition - his mark of 77.47m isn't enough to give him three more throws.

Image source, Getty Images