Owen Collins: Got a lot of time for Martyn Rooney. Honest, forthright and quite justified in his palpable, simmering anger.   

A huge roar rings out around the stadium as Usain Bolt and the rest of the Jamaica 4x100m team get their gold medals.

It's a ninth Olympic gold for Bolt. Incredible. I wonder where he keeps them all? 

Athletics with a bit of taekwondo...

Watch at the top of the screen. Or join us by tweeting to #bbcrio2016

Aimee Lewis
BBC Sport in Rio

If you thought the Olympic Stadium and the Maracana were where it was all happening - think again. At the taekwondo, Shaggy's Mr Boombastic is ringing around the arena as we wait for the fighting to begin again. The crowd are loving it, raising their arms, swinging their hips, hoping to get caught on camera. It's Saturday night, I suppose, the penultimate day, time to party. 

Image source, .

Martyn Rooney is in the BBC studio at Olympic Park and has just watched back a video replay that provides the reason for GB's disqualification from yesterday's 4x400m relay race.

Matthew Hudson-Smith was deemed to have had part of his foot outside the takeover zone and Rooney said:  "I just watched it for the first time and it is not conclusive. It is a track judge's opinion. There was no hawkeye like in other sports, it is a track judge's opinion and seeing it now makes me even angrier."

We saw a lot of disqualifications in the relays last night. Rules are rules, but unless someone is clearly cheating or impeding another athlete these decisions seem very harsh.

Throw an 800g javelin over 90m, get yourself a medal. Probably a gold.

That's the challenge for the men in the javelin final tonight. Only one man has hit the 90m mark this season which I guess makes German Thomas Rohler favourite.

Then again, if it's big tournament experience you're after perhaps Kenya's world champ Julius Yego is the man to beat.

Or is defending Olympic champ Keshorn Walcott going to retain his title?

Image source, Getty Images

If you missed the drama last night - Great Britain have failed in their appeal against disqualification from the Olympic men's 4x400m relay semi-final in Rio.

Nigel Levine, Delano Williams, Matthew Hudson-Smith and Martyn Rooney finished first in two minutes 58.88 seconds.

Leg three runner Hudson-Smith was ruled to have had part of his foot out of the takeover zone when he began running.

British Athletics said it was "hugely disappointed" and confident the team would have won a medal in the final.

The appeal was rejected because video evidence was inconclusive, meaning the decision of the referee must be upheld.

Britain clocked the third fastest time behind Jamaica and the United States, who ran in the first semi-final.

Denise Lewis
Olympic heptathlon gold medallist on BBC TV

When you get to that sort of age it is about motivation. To keep putting in the miles, staying meticulous with your diet and routine and I think Mo is an incredible ambassador for our sport.

Morgan Lake has cleared her opening height of 1.88m. Safe as houses.

Her best this season remember is 1.94m. 

Benjamin Smith: Waiting up for #MoFarah, external my 8 year old is still awake too and very excited #noschool, external

A reminder that Mo Farah tripped in the 10,000m final - but still won - and also fell during his 5,000m heat.

It's a congested field out there at times. 

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

Staying out of danger is the most difficult thing for Mo. He will be right at the back, keeping an eye on the rest of the field before moving forward. Mo's stride length takes up quite a lot of space and he has to be aware of that because others have to almost step over that back leg, which is what happened when he fell. If we see him in his customary position, at the front of the pack with two laps to go, then I can't see anyone challenging him.

After the triple triple, the double double. A run for greatness. His place in the history books is already confirmed but if Mo Farah wins tonight then he will truly become a legend.

Farah has three Olympic golds to his name already. Plus five world championships titles.

Image source, Getty Images

He will become only the second man in history win both the 10,000 and 5,000m titles in the same Games twice if he wins tonight.

The 33-year-old hopes to match the performances of the great Lasse Viren of Finland, who completed the double at the Munich 1972 and Montreal 1976 Games.  

Team GB are just two medals away from equalling their haul from London 2012, when they secured 65 medals.

The two needed to equal it that total could well come in taekwondo, as Bianca Walkden and Mahama Cho go for bronze.

Walkden is up against Morocco's Wiam Dislam in the women's +67kg bronze match, while Cho takes on home favourite Maicon Siqueira in the men's +80kg. 

If you want to see Usain Bolt throwing a javelin at 0140 in the morning (last night) - click this link.

GB athlete Morgan Lake goes in the women's high jump final, and if she can find her best form then she may have a chance of a medal.

Lake has cleared 1.94m this season, with world leader Chaunte Lowe only managing 2.01m.

Interestingly Katarina Johnson-Thompson jumped 1.98m in the heptathlon - the fourth best in the world!

She is not in the final though. 

Image source, EPA