Image source, Getty Images

By the way, before we move away from the relays for a bit there was more drama in the 4x100m men's relay heats earlier.

The Netherlands lodged a protest claiming Jamaican sprinter Asafa Powell had crossed into their lane during the heats.

But the Dutch, having review the footage with the race adjudicators, withdrew their protest. 

They probably realised you can't have a sprint relay final without Usain Bolt.

Daley Thompson
Two-time Olympic decathlon champion on BBC TV

Shara Proctor broke the British record and led up to the final round with a leap of 7.07m, before Tianna Bartoletta's 7.14m snatched gold, on Friday.

Michael Johnson
400m world record holder on BBC TV

Image source, Getty Images

The final is the last event of the championships on Sunday.

Could we see this little man emulate his famous father?

Image source, Greg Rutherford

This is Milo, son of new long jump world champion Greg Rutherford, wearing his dad's gold medal.

Image source, BBC Sport

BBC's Phil Jones caught up with the 4x400m men and Martyn Rooney, who spoke about competing in Beijing and missing the birth of his first child 

"Well done to my wife. It's been an interesting couple of days," he said.

"It's great to become a father for the first time. To miss the birth I have to make it worthwhile."

Image source, Getty Images

All four of Great Britain's quartets avoided mistakes earlier today to book their places in the respective relay finals.

Both 4x100m teams will compete in the last two races of Saturday, while the 4x400m combos compete on Sunday.

Asha Philip, Jodie Williams, Bianca Williams and Desiree Henry (Dina Asher-Smith was rested) finished second to Jamaica to reach the women's 4x100m final (13:50 BST).

The USA, Jamaica's main rivals, also qualified.

The men's team of Richard Kilty, Harry Aikines-Aryeetey, James Ellington and Danny Talbot also qualified second from their heat - behind the supremely strong USA team, that included Justin Gatlin.

The women's 4x400m team finished second to USA in their race, while Martyn Rooney (whose partner Kate, and former pole vaulter Kate, gave birth to their first child in the last few hours)  brought home the baton in first place for the men.

Image source, Getty Images

If there was one guy who would have dumbfounded teachers shouting "Don't run! Walk along the corridors" it would have been Matej Toth.

The 'whizz of strolling' eased to victory in today's 31-mile event in three hours, 40 minutes and 32 seconds, on a baking hot morning in Beijing.

He finished almost two minutes clear of his nearest rival, Australia's Jared Tallent. That included a toilet pit-stop.

"My heart-rate, my stomach, my dreams, my refreshment, everything, was under control," said Toth.

Japan's Takayuki Tanii, last year's Asian Games champion, took bronze.

It's daaaay eight in the Celebrity Beijing Bird's Nest:

10:00 & 11:20 BST:  Men's decathlon - javelin

11:30 BST:  Women's high jump final

12:15 BST:  Women's 800m final - GB's Shelayna Oskan-Clarke

12:30 BST:  Men's 5,000m final - GB's Mo Farah and Tom Farrell

12:50 BST:  Men's discus final 

13:10 BST:  Men's decathlon final event - 1500m

13:50 BST:  Women's 4x100m relay final - Brits

14:10 BST:  Men's 4x100m relay final - Brits plus Bolt and Gatlin

Mo Farah is ready, are you?

Get involved and send us your thoughts on today's action via #bbcathletics.

Image source, BBC Sport

We have British sprinter Ashleigh Nelson, Daley Thompson and Michael Johnson in the studio - with Gabby Logan presenting.

Unsurprisingly they're talking about Mo Farah.

Image source, PA

Mo, Mo, Mo, Mo, Mo. Remember distance running before Mo? 

• When British athletes used to come home a minute behind the winner.
• When repeated failures prompted the BBC to dig out the archive clips of Brendan Foster.
• When commentators used to say, "It's the Ethiopians and Kenyans dominating the race."

Then Mo Farah came along and put a stop to that, although they still occasionally show vintage Foster.

The 32-year-old Briton will attempt to win his third double - having won both the 5,000m & 10,000m at the 2012 Olympic and 2013 Worlds.

Will he do it?

The race is live on BBC One at 12:30 BST and on this website.