GB runner Shelayna Oskan-Clarke goes in the next 800m semi. A tough ask to get in the top two here. Can she squeak through?

Craig Steeples: Almost @jadejonestkd, external o'clock so may as well watch her win gold then watch the main man @usainbolt, external win his 8th gold!   

Olympic record! Ryan Crouser is having a blinder and he's just landed one at 22.52m! A bowling lane and then some. 

Image source, EPA

Paula Radcliffe
Women's marathon world record holder on BBC TV

As easy as they liked in the last 200m for the two in front. Just the first two to go through and the three fastest losers from the three semi-finals. It looked like Ajee Wilson, in third, eased and relaxed but she couldn't she needed to run as hard as she could. 

Just the top two to secure automatic qualification and it's Margaret Wambui who strides out to take the win, looking immensely powerful, edging out Francine Nyonsaba. Those two looked a class above. 

Caster Semenya.

It's a name which will resonate with a huge audience - more than most athletes - and all for reasons off of the track.

The South African made history when she won gold in Berlin seven years ago, but has been through the mill.

Athletics' governing body asked her to undertake gender verification testing. She has made no public comment since, and neither have officials, so we are left with what she was diagnosed with - hyperandrogenism, her testosterone levels far in excess of the vast majority of women.

Image source, Reuters

This excellent read from our own Tom Fordyce explains it all in detail, but basically after a few years in the relative wilderness she is back. And looking very, very good.

She leads the world's times this year with 1:55.33. Good enough for gold?

GB's Chris O'Hare burns out in the 1500m semi.

It is difficult to watch, he really puts everything into it.

Utter dejection.

Pauline Cornish: Why do I stay up till stupid o clock when I have to be at work in the morning...coz I love your banter.

The form runner in this semi is Francine Niyonsaba, she's clocked 1:56.24 which is the fastest time in the world this year.

Didn't the 1500m final have a last two laps of 1:57 the other night? Impressive! 

Paula Radcliffe
Women's marathon world record holder on BBC TV

This is a totally different Charlie Grice that turned up to the one we saw in the heats. There was a lot of pushing and shoving and he handled himself well. He didn't panic coming into the home straight.

There are two British athletes on display in the women's 800 tonight, with the top two in each semi-final guaranteed a place in the final.

In semi-final two Shelayna Oskan-Clarke runs, while up against Caster Semenya in the third race is Lynsey Sharp.

Sharp has the seventh-best time of 2016. Looking, well, sharp. 

Image source, PA

Ryan Crouser still leads - 6ft 7ins of man-mountain - he has hurled it out to 22.26m now. A PB at the right time. 

BBC One

Chris O'Hare after missing out on reaching the final: "I am not sure what happened. I put myself in the position. I felt fine with 200m to go and tried to turn it on with 100m to go and it just was not there. I am so disappointed because I wanted to do better for myself, my family and everyone watching back home. 

"I tried my best, I guess it is all I can do but it is disappointing when I have put all this work in and I thought I was good enough."

At the halfway stage it's a US one-two. Ryan Crouser leads with a throw of 22.26m, ahead of Joe Kovacs. 

Image source, Reuters

He literally could not look more relaxed...

In an eclectic field of hair and headbands, watch GB's Charlie Grice find his gap on the inside to brilliantly qualify in the 1500m

Steve Cram
BBC athletics commentator on BBC TV

O'Hare had nothing down the home straight and it is painful to watch. He didn't compete in London and he was desperate to get into the final of an Olympic Games but he just didn't have the legs.

Hard to watch this. Chris O'Hare blows up down the home straight, nothing in the tank, and he ends up on his knees all alone at the back of the field.

Ronald Kwemoi jogs to the win. 

Chris O'Hare goes for it with 600m to go but now he's heading backwards...

Brendan Foster
Olympic medallist and BBC athletics commentator on BBC One

Chris O'Hare is running a good race. He is strong at the finish and he is putting himself in within a chance of producing that finish.