Katarina Johnson-Thompson finished the day with a smile and a big thumbs-up to the camera after winning her 200m heat but she knows a collapse in the high jump makes winning a world heptathlon medal highly unlikely.

A time of 22.86sec improved her spirits and put her in fourth position overnight but the reaction when the stadium presenter Iwan Thomas optimistically called her the “golden girl of the sport” was telling. Johnson-Thompson waved him away, knowing she cannot hope to be atop the podium until she is able to conquer the mental demons that have repeatedly prevented her reaching her towering potential.

The 24-year-old collapsed on the crash mat head in hands after clearing only 1.80m in the high jump. She remained stationary for several seconds as if struggling to comprehend another major championships disintegration.

Desolation part way through the heptathlon is a familiar feeling for the Liverpudlian who suffered similar breakdowns at the Beijing world championships in 2015 and the Rio Olympics last summer. But never has it happened in the high jump, an event she relies on to put space between herself and the rest of the field.

The sodden track was being mopped after a heavy downpour when she entered the competition at 1.80m, clearing easily with her first attempt. But she opted to skip 1.83m and had to wait in the cold for 90 minutes before re-entering the competition at 1.86m. She clattered into the bar at the first time of asking and clipped it with her ankles with her second attempt. Clearly racked with nerves, she attempted to gee herself up before a final attempt in which she brought down the bar with her back.

Katarina Johnson-Thompson knocks the bar off. Photograph: Tom Jenkins for the Observer

Johnson-Thompson’s personal best of 1.98m, achieved in Rio, would have given her an additional 233 points and put her well in the mix after two events. But her medal rivals soared to new heights. Cuba’s Yorgelis Rodríguez got a massive personal best of 1.95 while the Belgian Olympic champion, Nafi Thiam, remained on course for gold with a first time clearance of 1.95. She was second overnight behind Germany’s Carolin Schäfer, who recorded personal bests in the high jump and shot put.

There were suggestions from Johnson-Thompson herself that these championships would be the advent of a confident, assured performer thanks to a switch from her long-time coach, Mike Holmes, to a new training group in France. She has lived in Montpellier since late last year and is coached by a trio of Frenchmen, led by Bertrand Valcin. But he could also be seen with his head in his hands in the stands.

The day had started well for Johnson-Thompson, who did a double fist pump and urged herself to “come on” as the camera panned to her on the start line of the 100m hurdles. She crossed the line in 13.33sec, just outside her personal best of 13.29.

But a poor high jump resurrected memories of Beijing two years ago, when three fouls in the long jump ended her medal aspirations. In Rio, a meltdown in the javelin meant a premature end to podium hopes.

There was better news for another of the few realistic British medal hopes as Sophie Hitchon qualified with ease in the hammer. The 26-year-old, who won Olympic bronze in Rio, threw 73.05m on her first attempt to advance to Monday’s final automatically as the third best qualifier.

“I think the thing is in qualification rounds is just to make it through, no matter how you do it,” said Hitchon. “You can do it in one throw or three throws as long as you make it, who cares really.”

All three of the British 100m women advanced to Sunday’s semi-final. The most experienced of the trio, Asha Philip, ran a season’s best of 11.14 to sail through. Desirèe Henry lit the Olympic flame as a schoolgirl at London 2012 so has happy memories of this magnificent stadium and got through in 11.32. She said Rio, where she won 4x100m bronze, could not match up to a home crowd.

“You think Rio and being at the Olympics last year was probably the biggest sporting event,” she said, “but to come here and be in London and see the whole stadium packed was a crazy experience. Five years on it is a dream come true to be competing here so I’m extremely happy that I was able to fulfil my goals.”

Daryll Neita was perhaps the most impressive of the three, running her second fastest time ever – 11.15 – to ease through to the semi-final.

Muir stays cool in tricky heat to keep medal hopes alive

Laura Muir is from a small town near Kinross in Scotland, a student vet who never drinks, save for a glass of champagne on Christmas Day. She is not one for silliness and so continued her sensible advance through the rounds, remaining a medal contender in the 1500m.

The 24-year-old looked to have plenty left in the tank, finishing a narrow second in her semi-final, behind Kenya’s Faith Kipyegon. She never dropped out of the top five spots required to qualify and an injection of pace down the home straight ensured she remained trouble free as she crossed the line in 4min 03.64sec.

It was a devilishly tricky heat on paper, containing both the world record holder, Genzebe Dibaba, and the Olympic 800m champion, Caster Semenya. While the latter jogged over the line, Dibaba was noticeably out of sorts and had to rely on a fastest loser spot to advance.

“It was a really strong heat,” said Muir. “That could have easily been a final so I was really happy. I was boxed in a bit, but I didn’t panic. I kept glancing up at the screen to check the gap behind because I didn’t want to waste too much energy but at the same time I know the likes of Semenya and Dibaba were behind me. I just thought I want to keep out of harm’s way and have a little bit up my sleeve if they come running past.”

Luvo Manyonga of South Africa celebrates winning gold in the long jump. Photograph: Fabrizio Bensch/Reuters

Laura Weightman ran a smart race in the second semi-final, taking advantage of her tiring rivals to qualify in 4:05.63. “I knew that to make the final I would have to run the race of my life and I think I might have just done that,” she said. “I don’t think words can summarise what it is like to compete out there in that stadium. I think I had a smile on my face the entire race.”

Almaz Ayana’s recorded a stunning 10,000m victory in which she covered a 5,000m split in 14min 30sec. The Ethiopian had to wait almost a minute to shake the hands of her rivals, crossing the line in 30:16.32 ahead of her compatriot Tirunesh Dibaba, who was second in 31:02.69. Agnes Jebet Tirop of Kenya rounded up the medal positions in 31:03.50.

Meanwhile, a thrilling men’s long jump contest was won by South Africa’s Luvo Manyonga, who leapt to 8.48m with his second attempt.

The British defending champion Greg Rutherford was absent through injury but Manyonga was pushed all the way by Jarrion Lawson of the USA who jumped 8.44m with his final attempt.