Katarina Johnson-Thompson's mum writes her a letter in Rio

What if your son or daughter, brother or sister were about to play out their childhood dreams before a watching world, the pressure of a nation heaped on their shoulders? They could succeed, yet they could fail. How would you feel?

Here, Tracey Johnson, mother of British heptathlete Katarina Johnson-Thompson (who lies fourth going into day two of the competition), writes a letter to her daughter, to tell her how she feels about the woman and the athlete she has become.

Tracey Johnson's letter to her daughter, Katarina

My dearest daughter Katarina,

When you were a little baby, an old lady took my hand and told me I had been truly blessed, that you were a very special and lucky baby. I thought so too, as every mother does about their own child, but I soon realised just how special you really are.

I wish you all the luck in the world and, whatever happens, know that, as always, I am very proud of you - not just for your athletic achievements but, most importantly, I am proud of the humble, grounded, wonderful woman you have become.

It has been an incredible journey. From my little girl who wanted to escape ballet classes as you preferred playing football with the boys, then watching you at your first school athletics competition, seeing you join Liverpool Harriers and compete in local, and then national, competitions.

Johnson-Thompson won the women's pentathlon at the European Indoor championships in 2015, setting a new British record in the process

You went on to world youth and junior competitions, then the Olympics, London 2012. It was almost surreal, sitting in the crowd watching my own baby girl up there with the entire crowd cheering. It was your dream come true. It was so great to see you achieving your goals. I was overwhelmed with happiness, and I cried with joy.

You have had your ups and downs and I have felt every one of those experiences with you every step of the way. It has been a rollercoaster of emotions, but your dignity when faced with obstacles and humbleness in victory shows such grace and strength of character.

It has been the most wonderful experience watching my little girl grow from school sports day to become an Olympian, bringing the wonderful world of athletics into our lives. Thank you for all the hours of enjoyment.

Johnson-Thompson started athletics after giving up ballet lessons

You have made a lot of sacrifices, especially through your teenage years, but your hard work, belief and determination have got you to Rio, your second Olympics.

I believe this is your time, go out there and give it your best. We will be with you every step of the way! Britain, Liverpool and all your family and friends believe in you and are supporting you.

Love you, my special, lucky baby.

Mum xxx