Great Britain have Luke Cutts in the men's pole vault looking for a place in the final.

The top 12 qualify, or a jump of 5.75m means automatic progress.

Cutts has a season's best of 5.40m so will have some work to do.

Image source, Reuters

At the front it's all about Frenchman Renaud Lavillenie. The world record holder is the defending champion and his best jump this season is a whopping 5.96m.

We want six! We want six!

It's quite hard to watch Katarina Johnson-Thompson at the moment as she stalks the outskirts of the track, practising endless phantom javelin throws but with no look of confidence in her eyes at all. 

This is not her strongest event and she has to work on it. 

Steve Backley
Four-time European javelin champion on BBC TV

At the moment this is putting so much pressure on Katarina Johnson-Thompson's 800 metres.

It is a difficult situation for her. She is clearly carrying some pain in her elbow, but I feel for her. A throw of closer to 40 metres is what is needed. 

One lap of the track, head down and go for it. Breathing hard, killer back straight. It's a punishing, punishing race. Unless you were Michael Johnson.

Image source, AP

Mind you the top three of this year's field made the heats look super easy, and we could have some quick times tonight.

LaShawn Merritt and Kirani James come head to head in semi one (00:30 BST), with South African world champ Wayde van Niekerk in the second. The top two in each are guaranteed a place in the final.

Britain's entrant Matt Hudson-Smith goes in the the third (00:44 BST).

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Katarina Johnson-Thompson would score 598 points from her first throw of 36.36m going into the 800m later on. It would leave her needing a special run to get in to the medals.

That decisive 800 is happening at 03:18 BST. Set that alarm. 

Image source, Reuters

Steve Backley
Four-time European javelin champion on BBC TV

Kat is so frustrated. It is slipping from her grasp. 

It stalled badly.

I don't know where she goes from here to salvage this javelin competition.

Image source, Reuters

It's a very tentative approach, Katarina Johnson-Thompson acting as if that javelin is totally alien in her grasp. Can she deliver? I wouldn't count on it and no, it's a really poor effort.

The trajectory of a released balloon at a child's party. It flops to the deck and she steps over the line. Don't even bother measuring that...

Steve Backley
Four-time European javelin champion on BBC TV

I want to see a bit of fight. The Katarina Johnson-Thompson we see in the high jump.

I want to see her give it an almighty lash.

How are you following?

The first action on the track tonight will come in the men's 400m. One of the best events, surely?

I'll bring you a list of names to watch shortly as the athletes circle each other in the warm-up room.

Callum Skinner will race Jason Kenny for a gold medal on Sunday. How are they preparing?...

Denise Lewis
Olympic heptathlon gold medallist on BBC TV

Kat needs to throw through the javelin. It is just hitting the air and stalling.

She needs to attack the javelin. All of the technical elements are not quite right.

Steve Backley
Four-time European javelin champion on BBC TV

The good news is that throw of 36.36m is fixable, but the bad news is that was just like all of Katarina's practice throws.

Golfer Catriona Matthew is there to lend her support to her fellow Britons.

I remember staying up super late to watch Michael Johnson run that 200m. The time is etched into my mind - 19.32seconds.

I never thought it would be beaten. He must have won by 40m!

Astounding. 

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

Image source, PA

Any time the Olympics come around you start to think about those days.

It is the 20th anniversary of my win in 1996 so there has been lots of revisiting.

You look out there, see what these athletes are going through and it does take you back.

The field is split into two for the penultimate event tonight - the javelin.

Katarina Johnson-Thompson goes in the first group which has just started, and has her chance to put the chasing pack under pressure.

Her personal best is only 42.01m though.

Image source, AP

Jessica Ennis-Hill and Nafi Thiam go in the second half of the draw from 01:18 BST.

Ennis-Hill has a PB of 48.33m and may need to match that, if Thiam gets near her own PB of 52.62m...

Take a look at how GB's Joe Joyce knocked out Cape Verde's Davilson Dos Santos Morais with one brilliant roundhouse right to go through to the quarter-finals.