Harry Poole
BBC Sport in Tokyo

Image source, Getty Images

Seeing Matthew Hudson-Smith struggling as he did in the heats was a huge surprise.

The Olympic and world silver medallist said he "felt flat" and his hips were "a bit iffy" as he scrapped through to the semi-finals in one of the non-automatic qualification places.

Hopefully it's an issue that he has been able to work through since Sunday. Otherwise, he could have a real fight on his hands to even have the chance to upgrade to gold.

Charlie Dobson, second on the British all-time list, will be desperate to make the final as the seventh-fastest 400m runner this year after going out in the semi-finals with a personal best run at last summer's Olympics.

As was expected of the fastest man over 400m this year, Jacory Patterson clocked the top time in the heats (43.90 seconds), with fellow American Khaleb McRae behind him with 44.25.

Zakithi Nene of South Africa won his heat (44.34) as did Bayapo Ndori of Botswana in 44.36.

Reigning Commonwealth champion Muzala Samukonga came third in his heat, in keeping with the Zambian's middling form this year.

The 33-year-old Kirani James rolled back the years to clock 44.66 and finish third in his heat - the Grenadian is looking to add to his full set of Olympic and World Championships medals.

Harry Poole
BBC Sport in Tokyo

Erm... I think Sydney McLaughlin-Levrone just jogged to the seventh fastest time in history?

It's the fastest time this year and she made it look that easy.

The world record is only 0.69 seconds quicker and that has stood since 1985. Crikey.

Image source, Getty Images

It's almost men's 400m semi-finals time!

Three British hopefuls progressed through the heats on Sunday, taking their place in today's semi-finals.

Charles Dobson lines up in lane four of heat two after reaching the semi-finals as an automatic qualifier.

Samuel Reardon (44.70 seconds) and Olympic silver medallist Matthew Hudson-Smith (44.68) both went through among the six quickest non-automatic qualifiers, even though both ran quicker times than Dobson (44.85).

All three will have to up their game if they are to rise above a competitive field.

Dame Jessica Ennis-Hill
Three-time world heptathlon champion on BBC TV

I'm blown away by the way Sydney McLaughin-Levrone runs. I don't see who takes her down, she is simply incredible.

Andrew Cotter
BBC Sport athletics commentator

Sydney McLaughlin-Levrone is such a class athlete. She has to be the favourite now! Crucially from a British point of view, Amber Anning is also through.

No hurdles? No problem for Sydney McGlaughlin-Levrone, who runs a world-leading 48.29 - a new American record - to win the third and final semi-final.

Great Britain's Amber Anning produces a season-best run of 49.38 to pip Nickisha Pryce to second place.

Pryce qualifies for the final as the fastest non-automatic qualifier, and is joined by Norway's Henriette Jaeger.

Ask Me Anything

Athletes competing for Great Britain and Northern Ireland have the option to wear two different coloured kits in Tokyo.

It has caused some confusion for viewers at home, especially in the men's 1500m semi-finals when Josh Kerr sported a blue and white striped jersey, while team-mate Jake Wightman wore a white sleeveless top.

A British Athletics spokesperson said athletes were given the choice to help their "individual needs, performance, preferences and comfort".

The blue kit is designed with aerodynamic sprint features in mind, while the white sleeveless top and shorts provide a lighter, traditional option for non-sprint athletes.

Read more here.

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Former world champion Salwa Eid Naser takes the second semi-final very comfortably in 49.47, with Cuba's Rozana Gomez second in a season's best of 49.78.

Isabella Whittaker takes third in 50.20, and for the moment is heading to the final as the fastest non-automatic qualifier.

The same can't be said of world number six Lieke Klaver, who finishes fourth and is out.

Great Britain's Victoria Ohuruogu finishes in eighth place.

Image source, Getty Images

Harry Poole
BBC Sport in Tokyo

Trying to make it on to the women's 400m podium was a hard enough task with the presence of Marileidy Paulino and Salwa Eid Naser.

And now hurdles star Sydney McLaughlin-Levrone has thrown her hat in the ring?!

It was always going to be a huge task ahead for Great Britain's trio to make the women's final given the strength in depth here.

After tasting world gold indoors earlier this year, following a fifth-place finish at Paris 2024, Amber Anning in particular will be desperate to have a shot at the medals.

Oh my word! World and Olympic champion Marileidy Paulino is cruising to the finish line, but suddenly slows down a few metres from the line and almost drops out of the top two!

The Dominican comes second, surrendering first place to Natalia Bukowiecka of Poland.

Henriette Jaeger comes third and will sit in the hot seat, along with Sada Williams.

Great Britain's Yemi Mary John comes last after struggling in the inside lane.

Dame Jessica Ennis-Hill
Three-time world heptathlon champion on BBC TV

Image source, Getty Images

How hard is it to switch from hurdles to flat?

The hurdles give you rhythm. 400m isn't far, but the speed and patience required is really hard to achieve on flat.

Image source, Getty Images

It's all go in Tokyo, it's time for the women's 400m semi-finals.

Great Britain are well represented with Yemi Mary John, Victoria Ohuruogu, and Amber Anning all in action.

Earlier this year, Anning, who came second in her heat in 49.96 seconds, became the first British woman to win an individual world indoor sprint title, when she claimed gold in Nanjing.

She was beaten in her heat by Marileidy Paulino, the reigning Olympic and world champion. However, it was Bahrain's Salwa Eid Naser, the Olympic silver medallist, who ran the fastest qualifying time (49.13 seconds).

Sydney McLaughlin-Levrone (USA), a former 400m hurdles world champion, has her sights set on the USA record of 48.70 seconds, which has stood since 2006, and ran 49.41 to win her heat by over a second.

Image source, Getty Images

The final of the men's hammer throw has just got underway.

Reigning champion Ethan Katzberg looks in a healthy position to defend his title. Achieving 81.85m in qualifying, the Canadian and Olympic champion looks head and shoulders above his competitors.

Paweł Fajdek of Poland is the closest to catching him followed by Germany's Merlin Hummel and Bence Halasz of Hungary. They all threw over 78m in qualifying.

Eivind Henriksen of Norway achieved a season's best of 77.70m in qualifying, meanwhile USA's Rudy Winkler achieved his personal best of 83.16m earlier this year.

Can anyone catch Katzberg?

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

You knew straight away Grant Holloway was going to be in bother. That'll be so frustrating for him because he knows what he is capable of. The world title will go to somebody else.

BBC iPlayer

We're back on BBC Two for the television coverage.

You can also watch live on BBC iPlayer or by clicking the link at the top of this page.

If you do miss any of the key moments, the daily highlights show will be available to watch on iPlayer, Red Button and online from 17:00, and BBC Three from 19:00.

All times are in BST.

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Jamaica's Tyler Mason, who ran a season's best to produce the fastest time in the heats, has just run a personal best of 13.12 seconds to win the third semi-final.

Roars around the stadium as Japan's Rachid Muratake is confirmed in second place in 13.17.

USA teenager Ja'Kobe Tharp (13.19) takes third to clinch a fastest loser spot, as does France's Just Kwaou-Mathey (13.22), who is *just* faster than Demario Prince (Jamaica) and Lorenzo Simonelli (Italy).

However, reigning world and Olympic champion Grant Holloway is out after fading in the second half of the race once again. He finished sixth.

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Update from the men's high jump final.

As expected, Olympic champion and world number one Hamish Kerr, world indoor champion Sanghyeok Woo and European indoor champion Oleh Doroshchuk have all cleared the opening height of 2.20 metres with their first attempts.

Australia's Yual Reath achieved his season's best in qualifying (2.25m), but he needs a third attempt to sneak over 2.20m and avoid elimination.

Image source, Getty Images

That's more like it from Cordell Tinch. The American, the fastest hurdler in the world this year, only finished third in his heat yesterday but came out on top in the second semi-final in 13.16 seconds.

Switzerland's Jason Joseph takes second place in 13.18.

Demario Prince (Jamaica) and Lorenzo Simonelli (Italy) run 13.22 to knock Shusei Nomoto and USA's Dylan Beard out of the fastest loser race.

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

Image source, Getty Images

Dylan Beard is in big trouble. Sometimes you can over-race, and that could be an issue here.