Laura Muir looking smooth, strong, serene almost. At the front at the bell...

Just before heading to the medics to get her leg injury looked at after she was caught with a spike down the front of her leg, Laura Weightman has quickly spoken to BBC One.

After reaching the final of the women's 1500m, she said: "I'm so happy to reach the final. I was so nervous, I didn't think I would do it. I took it on and I'm pleased I took the chance."

Jamaica's Shelly-Ann Fraser-Pryce is all smiles after receiving her bronze medal for coming third in the women's 100m on Saturday.

Image source, EPA

Genzebe Dibaba has had a shocking season but remains one of the favourites for this medal, she is up there with Laura Muir at the moment. 

Top five go through remember. 

Brendan Foster
Olympic medallist and BBC athletics commentator on BBC One

That was a very good performance by Laura Weightman, she really ran well. She is in some sort of distress, she had a spike down the front of her leg. It is a bad one.

Tom Fordyce
Chief sports writer in Rio

The lane draw is in for the men's 100m final: 1. Bromell 2. Simbine 3. Gatlin 4. Vicaut 5. Bolt 6. De Grasse 7. Meite 8. Blake

Laura Muir going in the next semi-final for GB. She looks nervous. Time for a good time...

Usain Bolt wins his 100m semi-final heat in 9.86 to set up a showdown with Justin Gatlin.

Luke Reddy
BBC Sport in Rio

Image source, .

Poor old Kei Nishikori. That Olympic final has left some people with a look of confusion on their face as if they've forgotten someone came third. 

Andy Murray has a medal around his neck. There's still singing for Juan Martin del Potro. At 141 in the world rankings he put up a fight worthy of any Olympic stage.

Gold looks good on Murray though and he ensures the day ends with more golds for Team GB than at any other overseas Games.

I don't know how much contact is legal on the line in a 1500m race but Laura Weightman must have been on the limit.

She has taken a nasty cut to the shin in the process.

As expected, Faith Kipyegon won it in 4:03.95.

Laura Weightman makes it! She was tying up badly down the home straight but puts in a shoulder barge on the line and staggers over the line.

Great effort.

Laura Weightman leads at the bell for GB...

It was the moment Canadian sprinter Ben Johnson stunned the world by winning the 100m final at the 1988 Olympics in a world record of 9.79 seconds.

But when BBC presenter Des Lynam was handed a piece of paper, he warned the nation he was reading about the "most dramatic story of this Olympics, or any other".

Johnson was stripped of his gold medal after testing positive for steroids and sent home in disgrace. 

Watch the video below (available to UK users only).

Michael Johnson
Four-time Olympic gold medallist athlete on BBC One

The line-up is not as good as it was last year (in the World Championships) and Justin Gatlin is not as fast as he was last year.

I thought Bolt looked like what we expected. When he is healthy, and hasn't had the injury problems that he has had over the last two years then he is unbeatable and I don't expect any hiccups.

Janine Pingree: Blimey, Bolt looked like he was having a stroll in the park!!

Andy Shepherd: Gatlin looked like he was going hard in that run. Usain Bolt looked so so easy and a tenth ahead.

Helles Mammut: This is Bolt's gold to lose, Gatlin 0.1s slower despite going almost full throttle... get ready for another Usain Bolt show.

The first five runners in each semi go through from each semi. Laura Weightman runs for GB in this first one.

Can she make it through?

Fastest in the world this year is Faith Kipyegon. She is favourite to win this semi.

Michael Johnson
Four-time Olympic gold medallist athlete on BBC One

Could Usain Bolt get emotional ahead of his last Olympic 100m race?

No. Usain Bolt is not that kind of guy.

He's thinking "I want to go out there, win gold, then move on with my life, because that's what I can do, I'm Usain Bolt."

And this is his last Olympics, I was speaking to him the other day, this isn't a Michael Phelps thing,

Image source, AP

A glimpse of a rare British female medal hope on the track next as Laura Muir goes in the 1500m semi finals.

She carded a superb 3:57.49 earlier this year. The second quickest in the year.