Usain Bolt looking out for his mates according to the Jamaica Gleaner editor.

Image source, EPA

Ahead of London 2012, Laura Muir arranged a placement on a dairy farm in Perth knowing that the early-morning milk rounds would mean her evenings would be free to watch the athletics action.

Spin forward five years and the Scot - still studying to be a vet - is right in the centre of the action.

The British record holder made her way comfortably through the heats yesterday, but has landed a stacked semi-final.

Kenya's Faith Kipyegon and Ethiopia's Genzebe Dibaba - the gold and silver medalists from Rio 2016 - are in her rac, along with Olympic 800m champion Caster Semenya, who looked very comfortable at the trip up in distance.

Great Britain's Jess Judd who progressed through the heats with a gutsy front-running display is also in this semi.

The first five go through in each of the two semi-finals, with two fastest-loser spots.

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

Reece Prescod was really impressive the way he picked up speed from such a poor start. He overcame his start, kept his focus, executed his race and ran through the field. It was an amazing performance to get into the final.

Image source, PA

Great Britain will have two men in the 800m semi-finals after Kyle Langford and Elliot Giles got through this morning's heats.

Langford, who is just 21, clocked 1:46.38 to come fifth and edge through as a fastest loser. Giles needed no such thing as 1:45.86 was enough for third in his heat.

This of course is the event only David Rudisha is allowed to win in recent years but with the big Kenyan out with injury, focus is on Botswana's Nijel Amos. He won his heat easily and will have his eyes on only the third World Championship medal of his country's history.

Belgian Olympic champion and hot favourite Nafi Thiam has been putting together a rock-solid day one.

Her second shot put is no improvement, but her opener of 15.17 is only 18cm down on her personal best,

Darren Campbell
Former British sprinter on BBC Radio 5 live

Usain Bolt, again, was so slow to react at the gun and was behind Coleman but then he went into another gear. Bolt started to have his little look across as if to say 'young man I'm here and I'll see you in the final'.

I've no idea who will win the final. Actually, I've been bigging up Christian Coleman and I will say... Usain Bolt will win it.

Well, well, well.

That was a race of two halves.

Christian Coleman comes tearing out of the blocks, Usain Bolt left choking on dust.

Bolt cranks into life around 50m and finishes just a hundredth of a second down on the American.

But I think Coleman was easing off.

Cj Ujah down and out with a time of 10.12.

Image source, Reuters

Usain Bolt has checked his blocks, digging his spikes into place as though he is wearing crampons on K2.

Cj Ujah wants more decibels as his name is read out after the big man's.

They drop to a starting position.

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Colin Jackson
Two-time world 110m hurdles champion on BBC TV

Usain Bolt's semi-final is red hot. And with Christian Coelman in the same semi-final it means we could see two heavyweights go head to head early. The American looked good yesterday.

Will Usain win gold tonight? "Yes he will, 9.81".

Image source, Getty Images

They have saved the best for last.

The third and final semi-final features Usain Bolt - a man with more medals than a south American army general - against the fastest man in the world this year - American Christian Coleman.

The reigning king against the rebel prince.

There will be plenty trying to spoil the party and keep the favoured two from the automatic qualifying spots though.

Britain's CJ Ujah - who has won three times on the Diamond League circuit this season - will be going hard alongside France's Jimmy Vicaut. Both have gone under 10 seconds this season while Antigua's Cejhae Greene looked quick.

Colin Jackson
Two-time world 110m hurdles champion on BBC TV

A brilliant run by the young man, brilliant. This type of run will improve him and he's going to have a nice, nice progression in his sprinting life.

Image source, PA

Darren Campbell
Former British sprinter on BBC Radio 5 live

That was a terrible start from Reece Prescod but he didn't panic. He's new into the sport and that takes time but he is the new talent. He can go so far in this sport. That's a fantastic performance.

Yohan Blake had it in the bag from 50m, but the story was Reece Prescod.

The Briton was dead last at 40m, but his stride suddenly clicked in and he just had Christopher Belcher inside him on toast.

The rest of the field followed and he nicked second just in time.]#

Well played. He goes into the final with a time of 10.05.

Reece Prescod, out in lane nine, is one of the last to settle into the blocks.

Image source, Rex Features

The second of three semi-finals for the men's 100m.

Yohan Blake is in this one, but a run of injuries over the last couple of seasons, including a groin tweak a fortnight ago, seem to have sapped some of the mojo that made the Jamaican 2011 world champion.

Reece Prescod was dubbed the British Bolt as a junior. A little hyperbolic, but the similarities are there with the 21-year-old Londoner topping out at six foot four in his spikes. He won the British trials in 10.09 in Birmingham in July.

Katarina Johnson-Thompson has had her first lob of the shot.

The Great Britain heptathlete hits 12.01m. Underwhelming considering her season's best is 12.85 and personal best is 13.14.

Two more to go for KJT.

Steve Cram
BBC athletics commentator on BBC TV

Image source, Reuters

I was chatting to the American team management before the race and they were playing down Gatlin, saying he’d been changing too much in his set-up before the event, and that wasn’t a Gatlin performance. One of the slowest semi-finals he will have run to make a final.

Darren Campbell
Former British sprinter on BBC Radio 5 live

Justin Gatlin started well but I think he tried to work too hard, trying to put down a time to scare his rivals, maybe it was because of the boos. But that meant he wasn't relaxed and Simbine was very relaxed and looks ready for business.

That was more like it from Akani Simbine - who has been sub 10 seconds eight times in 2017.

Justin Gatlin took the second automatic qualifying spot.

Great Britain's James Dasaolu was well down in 10.22 and fifth behind Meite and Forte.

We won't be seeing him again.