Let's do some clock-watching. Because Dina Asher-Smith will be. The Briton needs the third-placed finisher in the final semi-final to run less than 22.49 seconds. Let's find out...

Two Britons are through to tomorrow's long jump final. Lorraine Ugen qualifies in eighth, while Jazmin Sawyer sneaks through in 12th. Shara Proctor is unable to join them though. She is out in 18th.

GB's Jodie Williams after finishing eighth in her semi-final: "I'm really disappointed with that - that's not what I wanted to come out and do. 

"But I feel so fortunate to even be here. My coach said to me before just remember 'you've done it, you've accomplished what you wanted to accomplish, you're at the Olympics'.

"Only 24 people every four years make the Olympic semi-final. In hindsight I'll be OK with it. but right now I'm disappointed."

Colin Jackson
Two-time world 110m hurdles champion on BBC One

Jodie Williams was always going to be under pressure. She has struggled getting her fitness levels up and getting power work in. She will get healthy again, and will be back to her sprinting best soon enough.

The diminutive figure of Marie-Josee Ta Lou powers through to win the second semi-final, the Ivory Coast runner clocking 22.28s. Ivet Lalova-Collio joins her in progressing automatically. No joy for Jodie Williams as she finishes last.

It's not all over yet for Asher-Smith. She's hanging on in there in a fastest loser spot with one semi final left.

So it is Dafne Schippers and Elaine Thompson who go through to tomorrow's final automatically after the first semi-final. Dina Asher-Smith crossed the line in 22.49.

Second semi-final up now, with Asher-Smith's team-mate Jodie Williams looking to progress.

Image source, Reuters

GB's Dina Asher-Smith on finishing fourth in her semi-final: "I'm not happy with that, I know I can do much better. My bend was good and I think it was good until 150m, then I got into a wrong body position and it is hard to correct and makes you slow down. 

"I'm not sure if it will be enough to make the final but I'll have to wait and see. It was a tough semi-final and when I saw the line-up written down I thought it was more like a final than semi-final."

Here's Robbie Grabarz. One last chance to keep alive his medal hopes as he goes for his third attempt at clearing 2.33...and he can't do it. The bar comes clattering down and he is straight up onto his feet to applaud the crowd, but he looks hugely disappointed.

Image source, AFP

Steve Cram
BBC athletics commentator on BBC One

Dina Asher-Smith just might have overcooked the bend but that's what she had to. She had to go out hard and she had no choice. There were some tired legs out there at 50m. It's a difficult balancing act, if you get it perfect then you finish strong, if you go a tad too hard then that's what happens.

The crowd goes wild as Brazil's Robson Conceicao wins gold in the men's 60kg lightweight for Brazil after unanimous decision.

Here's his winning performance.

Dina Asher-Smith is quick out of the blocks and in a great position at the bend. It's looking good, but Dafne Schippers and Elaine Thompson turn on the afterburners and it is between the two of them heading into the final 50m. It's Schippers who edges it, clocking 21.96 seconds, with Thompson second and Deajah Stevens coming through to beat Asher-Smith to third. 

Brazil's newest national hero has wandered into the BBC Sport studio. It's pole vault gold medallist Thiago Braz da Silva. And he's still running on adrenaline after last night's heroics.

"I only slept for one hour and a half hours last night and I have done interviews all day. it's been very busy!" he says.

"Before the Olympics I was thinking to do my best - to get one medal for Brazil I didn't know which colour. Then it became gold! For me it was a surprise. An amazing night."

Earlier tonight, Great Britain's Jack Green loses his rhythm and stride in the men's 400m semi final and was disappointed with his time of 49.54s, leaving him in an equally disappointing eighth place. 

GB's Dina Asher-Smith is determined to win a medal in Rio. She cruised into the women's 200m semi-final and could even afford to ease off towards the end to conserve energy as she qualified second. Her reward, though, was to be put in the tougher of the two semi-finals. She's up against 200m world champion Dafne Schippers now.

Speaking of Robbie... 

After a controversial jump where his jump was disqualified even though the white flag went up before the bar falls, Robbie Grabarz is cheerful again after having that decision reversed.

Take a look at the decision earlier here.

...same again at the second attempt for Robbie Garbarz. One bite of the cherry left...

The bar is raised to 2.36m and Canada's Derek Drouin makes it look easy. He is up and over like a salmon. No bother. Robbie Garbarz has a tough act to follow, too tough. He smacks into the bar with his first attempt.

What a run! Ireland's Thomas Barr wins it! He can barely believe it himself. Barr whoops with delight as he crosses the line in 48.40 seconds. He's through to tomorrow's final!

We're heading into the third round of qualifying for the women's long jump and two of the three Brits looking to make it through are well placed.

Lorraine Ugen is currently seventh after jumping 6.65m while Jazmin Sawyers is on the bubble. Twelve go through and she is currently 12th after a 6.49m.

Shara Proctor needs to find a bit more. A 6.36m with her second effort is only good enough for 18th.

Image source, AP