Venue: Hayward Field, Eugene, Oregon Dates: 15-24 July |
Coverage: Watch live on BBC TV, BBC iPlayer, BBC Sport website and mobile app (UK only) |
Before her world title defence, Johnson-Thompson changed her coach to give her the best chance of winning an Olympic medal.
A five-year relationship between a British heptathlete and a Frenchman ended in 2020.
After moving to Florida, the world champion split from Petros Kyprianou as it "just wasn't working for me out there".
She said that she wanted to make the decisions sooner than later.
Valcin helped Johnson-Thompson win a world gold medal in the fall and she has returned to the UK to work with Moore, who has coached her before.
She decided to return to her hometown and move forward without Petros.
I believe this is what it is and I have to do what's best for me.
It ended in a way that was mutually agreeable. I didn't want to cause unnecessary headlines by getting into it.
As well as adjusting to a new coach before this year's world championships in the USA, which start on Friday, 15 July, Johnson-Thompson is still returning to full fitness after various injury problems.
She missed last year's Tokyo Olympics because of a calf injury, only to return in time for the 400m.
In Gotzis in May, Johnson-Thompson's score was her third lowest since becoming world champion with a British record of 6,971.
Two-time Olympic champion Nafi Thiam of Belgium is looking to win the heptathlon for the second year in a row at this year's world championships.
Johnson-Thompson said that he felt like he was in the best shape of his life going into the competition.
I had faith in my ability to win but at the same time I was thinking about what would happen.
I knew I was in good shape and I was going to put a good score out but I didn't care about my medal.
It has been shifted because I have a new coach. It doesn't mean that I can't get a good score, I feel like it's a different mindset, but it doesn't mean that I can't get a good score.
Success is something that is individual to each person and success for me would be getting a good score out this summer and being proud of what I've put out. I'm in a different place.