Reigning champion and European record holder Karsten Warholm is in lane 4, with Brit Chris McAlister in lane 9.

A bit of a mess of a race that! Hurdles hit all over the shop and Brazilian Alison dos Santos comes through to win in a PB of 48.35.

Kyron McMaster ties up to finish third - the top two go through by right so he'll have to wait.

McMaster hits the first hurdle! Stays up though.

Here comes the first semi, none of the big guns in this one. Kyron McMaster is useful though.

Elliot Giles is through and his time of 1:45.53 is the fourth-fastest by any runner across the 800m today.

He says: "It was more mindset. KISS - keep it simple. I knew what I needed to do. I don't need to over-complicate it, just run. Richard Kilty said, 'over analysis leads to performance paralysis'. That has stuck with me. All we have to do is run and we will see what happens."

Potentially one of the best events this year - the men's 400m hurdles semis are up.

Before this year, to run under 47 seconds and lose seemed unfathomable. However, that’s what happened at the Diamond League final in Zurich. With three of the four fastest 400m hurdlers of all-time pushing each other and still arguably reaching their peak, sub-47 performances could become commonplace.

Karsten Warholm, Adberrahman Samba and Rai Benjamin are the men to watch.

To confirm, British trio Elliot Giles, Kyle Langford and Jamie Webb are all into the semi-finals.

Good effort lads.

Kyle Langford speaks to BBC Sport after clocking a time of one minute and 46 seconds. He looks braced to win through as a fastest loser but has been seen clutching his left knee.

"I was feeling alright and got clipped and kneed myself," he says. "I used to do that a lot in the past, i am so clumsy. I think I will be fine. I get better as rounds go on. I am disappointed by how it went there. I feel a bit embarrassed. With how I have been training I should be winning those heats. I will get better with the heats and rounds.

"There are a lot of great athletes here. The 800m is the hardest one to qualify in for the final. I am going for the medal. Once you get to a final, it's an even playing field. It will be hard but I have it in the tank."

Elliot Giles leads the field around into the home straight - and holds on! Wins the heat in 1:45.53. Superbly done that!

Brit Elliot Giles describes himself as “unorthodox”; he’s converted a bus into a luxury motorhome and will hope to be a driving force in this heat.

Amel Tuka and Clayton Murphy have both gone fast this season.

Steve Cram
BBC Sport athletics commentator in Doha

I think Langford will qualify as a fastest loser. Hopefully his knee isn't too much of a problem but he is grimacing.

Kyle Langford tries to come wide and kick but he hasn't got the legs - he's down in fifth and holding his left knee at the finish too.

It's won by Emmanuel Korir of Kenya in 1:45.13.

If Langford is fit to carry on he may be quick enough there to get through as one of the fastest losers.

Saj Chowdhury
BBC Sport in Doha

With the hugely unlucky Nijel Amos out with an Achilles problem it looks like it might be a fight between Donavan Brazier, Ferguson Rotich and Emmanuel Korir for gold.

Botswana athlete Amos, the fourth fastest ever, is pretty much the Colin Montgomerie of athletics - brilliant throughout the season but unfortunate when it comes to the majors.

Steve Cram
BBC Sport athletics commentator in Doha

Langford hasn't been in the best shape. He has had injury problems for around 18 months. He had an altercation with an official at one meeting and had to appear before a disciplinary committee. It has affected him mentally. He is a sensitive soul and I think he has struggled to put all that behind him.

Disappointed to come fourth two years ago, Kyle Langford has had an eventful 2019, with some well-publicised misdemeanours and a dislocated knee which he feared would end his season. US-based Kenyan Emmanuel Korir is capable of being seriously quick.

Unfortunately Briton Harry Coppell will be unable to take part in the qualifying competition this evening and has withdrawn from competition following aggravation of a hip injury in his warm up.

The pole vault has just got going.

Mark English went out hard from the gun for Ireland, gutsy. He's swallowed up though and in a packed finish it's Ferguson Rotich who wins it.

Jamie Webb, who qualified by virtue of finishing third in his 800m heat, tells BBC Sport: "Only one thing that mattered today was top three. Job done. Top three tomorrow and top three in three days, easy isn't it?

"I'm bad for being sick. The humidity. It just knocks you. It's really difficult to breathe. You have to race smart but it's wide open. I feel really ill."

On saying this, Webb crouches down and that's the interview done. The conditions are gripping these athletic wizards.

Top three go through. Jamie Webb took third. JUST.

World indoor and European champion Adam Kszczot is up against quick Kenyan Ferguson Rotich. Outsider Mark English is, er, Irish.