There we go! Mahama Cho gets in a headshot but lands on the floor as well. Three points for the British fighter and a penalty point awarded to his opponent.

Round one done and it is a stalemate. No separating Mahama Cho and Maicon Siqueira but Cho has won his first battle. He has quietened the home crowd.

Round two is up now.

Caster Semenya in second at 600m, but here she comes...

Francine Niyonsaba is the second fastest in the world this year and she takes the lead at the bell...

Caster Semenya leads them out, she wants to control it from the gun. 

You've got 15 minutes to Mo.

Go time. 

Mahama Cho is potentially three rounds away from a bronze. He's not rushing this, though. Staying patient and defensive as he tries to frustrate his opponent and the hostile crowd.

GB's Lynsey Sharp believes she can win a medal tonight. She looked super slick in the semis. Again, it could come down to pacing. Having said that, Caster Semenya may Rudisha it from the gun. 

Caster Semenya patrols up and down her lane, awaiting the gun. She has not lost a race this year. She doesn't look ready to lose one here.

Can she challenge the world record?

Mahama Cho now has the chance to win bronze and take GB's medal total to 65 in Rio. He's got a tough fighter and a tough crowd to get past though. He's up against home favourite Maicon Siqueira... 

Martyn Rooney tells BBC Sport he's even more angry at GB's disqualification after seeing a replay of the controversial incident for the very first time.

Morgan Lake has cleared 1.93m! She is still in the final. All going on. 

World champion Julius Yego of Kenya has a brilliant style - all or nothing.

He nearly propels his whole body past the line as he launches his first effort but it's clean - and it's big.

A season's best of 88.24m to take the lead. 

As mentioned earlier, the women's 800m world record  is the longest standing record in track and field.

It has stood since the summer of 1983.

Here are a few others which are long overdue a break:

Image source, Getty Images

Women's 400m - 47.60 (October 1985)

Women's 100m - 10.49 (July 1988)

Men's long jump - 8.95m (August 1991)

Men's triple jump - 18.29m (August 1995)

That's the way to make up for losing out in the semi-final! Bianca Walkden's aggressive approach pays dividends as the Liverpool fighter beats Morocco's Wiam Dislam to take the bronze medal.

That's 64 medals in total for GB now, one away from the London 2012 haul...

Tom Fordyce
Chief sports writer in Rio

Fabulous from Centrowitz in a classically messy championship final - got his tactics spot on as all others jostled and waited, in the right position when the real race began, with a speed and endurance that belies the injuries he had endured this years. A very popular winner.

We could see the conclusion to a fascinating Olympic tale tonight as Caster Semenya is red-hot favourite to win the 800m.

Semenya, 25, has had a colourful and controversial past, but she is also in the form of her life. 

Image source, Getty Images

In April she won the 400m, 800m and 1500m at the South African Olympic trials in the same afternoon, without looking remotely challenged. At the Diamond League in Monaco she ran 1:55.33, the fastest 800m since 2008.

Here in Rio, should she change her usual tactics and run hard from gun to line, Jarmila Kratochvilova's world record of 1:53:28 - the longest standing record in track and field - could easily go.

You can read this - and much more - from chief sports writer Tom Fordyce.