What's happening in the men's hammer? Firstly, thanks for asking. Secondly, Nick Miller has fouled twice. Third attempt... he twirls like a ballerina... the hammer lands at 72.94m which isn't enough to progress to the latter stages. 

Image source, Getty Images

"Initially, I'm really disappointed," Niall Flannery tells Phil Jones. "After yesterday I was quite confident of running a 48.50 which would have got me into the final. It wasn't as smooth as yesterday and the bit that went wrong yesterday went worse today, which is annoying. Hopefully next year it'll be a different story."

Michael Johnson
BBC Sport athletics expert & 400m world record holder

Image source, AP

The third, and final, men's 400m hurdles semi-final upon us and this one features Briton Niall Flannery, the man with Gary Barlow's haircut circa early 1990s. 

Flannery makes up ground coming down the home straight and finishes fourth. Could that be enough to go through as a fastest finisher? Nah. 

A fabulous finish to the race, though, with Michael Tinsley (48.47secs) just getting the better of Kenyan Nicholas Bett (48.54 secs). Two Kenyans are into the 400m hurdle final.

Image source, AP

Jacob Avers:  The Union Flag was upside-down for Mo's gold medal ceremony.

Bethan Roberts:  Nice to see the union flag flying high but upside down hopefully they can correct for @J_Ennis, external

Stan Flemming: Where does Michael Johnson buy his shoes? I want a pair like that! 

Mo Farah is on screen chatting about his Super Saturday V2. Looking ahead to the 5,000m heats, he says: "I've got three more days, which is enough and hopefully go out there and see what happens. There's a great team spirit here and I just want to keep smiling and keep doing what I'm doing."

Ali Jawad:  My anticipation for the 100m final today is through the roof.

Maisie-Rose:  Unbelievable performance from @J_Ennis, external - and to do it all so gracefully with sportsmanship and a smile.

Sean from Enderby:  Let's see if this Usain Bolt lad is faster than Vardy or Schlupp then.

Wowzers. People have been complimenting Michael Johnson for his sand-coloured suede shoes - but wait until you see Johnny Dutch's spikes, inspired by the Stars and Stripes. 

The American should have added propellers to the heels, though, because he messed up on the final hurdle and has failed to qualify for the men's 400m hurdles final.

He's on his knees, shaking his head. He was in the lead down the home straight but his hope of glory is over.

Image source, Getty Images

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"Usain Bolt got it wrong in the execution of his race yesterday in qualifying, but that bodes well for him. It's something he can look at with his coach and make sure it doesn't happen again today."

Usain Bolt goes in the first 100m semi-final at 12:10 BST

Here's an exciting development. Video in the live text! Goodness knows where technology will take us next. Anyway...

Who will win the 100m showdown to end all showdowns? Well, we've got BBC expert Michael Johnson on the case.

The men's 400m hurdles heats have begun. The deal? The top two qualify, plus the two fastest losers. Kenya's  Boniface Mucheru Tumuti once again impressive, clocking a winning time of 48.29 seconds. There's no Bershawn Jackson, of course, after the world number one failed to qualify to the semi-finals. 

American Kerron Clement also through. "He could be a major contender in the final," says Michael Johnson in the studio. We hear you, Michael.

Floyd Kelly-Lord: Love listening to Michael Johnson talk about athletics.

Rustovski: The wardrobe dept never has to work too hard to get Daley T the legend ready for being on air. #adidas, external#bbcathletics, external

James Hughes:#Bolt, external needs to win today for the integrity of the sport of athletics!

A disappointing start for Nick Miller but he has further opportunities to readdress and readjust. 

Adam Gemili is not competing in the men's 100m, of course, because of injury so the European 200m champion has been on work experience with BBC Radio 5 live and is eyeing Darren Campbell's job. 

Pamela Brown: Good luck Nick Miller in the hammer final.

PtheP: Gutted for @JohnsonThompson, external in the heptathlon. Maybe just go win the long jump instead?

Image source, PA

Daley Thompson
Two-time Olympic decathlon champion on BBC TV

"KJT is probably thinking to herself that she has no idea what went wrong. She's going to be feeling so bad right now. She's a fraction over, but it's a fraction too far." 

Denise Lewis
Olympic heptathlon gold medallist on BBC TV

"She's going to have to work on the mental side of heptathlon because it's an ever-changing event. I've been encouraged by what I've seen from her despite what's happened. We're talking about a fraction the distance by which she got it wrong."

Image source, PA

Michael Johnson
BBC Sport athletics expert & 400m world record holder

"It's about competition management. There's a lack of that from her at the moment and that's a shame because she's such a talent. These things are avoidable."

Image source, Reuters

There's been quite a bit of reaction to Katarina Johnson-Thompson's disappointing performance earlier. Here's what the experts have had to say about the young Briton... Stand by! 

Britain's Nick Miller is in form and shortly goes in the hammer final, starting at 11:30 BST.

He threw 77.42m in the qualification pool - to qualify in second place - and broke the 31-year-old British record last month.

Can he win a medal this afternoon? His performance in qualifying on Saturday was Daley Thompson's highlight of day one so who knows what the great Mr Thompson will say Miller win a medal. 

Image source, Getty Images