Captain David Beckham was visibly moved when he walked on to the pitch at Old Trafford holding Kirsty's hand while her oxygen cylinder trailed behind her.
To the millions who watched, Kirsty, who is terminally ill, was a brave girl battling against insurmountable odds.
But anyone who has ever spoken to her will know that her story is one of hope and a remarkable courage that has raised more than £1million for other sick children.
In 1999, Kirsty's parents, Stephen and Lynn, were told that their daughter, who was born with her heart back to front, was unlikely to reach her fourth birthday.
Aside from her heart condition, Kirsty was also born with stomach problems and some of her organs, including her liver, in the wrong place.
But Kirsty has not only defied doctors' predictions, she has spearheaded a campaign to raise £5million for a children's hospice.
She was picked to raise the money for Francis House in Manchester, where she has been treated since her birth in 1995.
The hospice costs £1.4million a year to run and relies almost entirely on donations. The Kirsty Appeal for The Rainbow Family Trust has now raised more than £1million.
Kirsty's campaign has seen her meet Prince Charles and Tony Blair as well as appeal patron Sue Johnston and her Royle Family co-star Ricky Tomlinson.
She also helped Victoria Beckham open the Harrods January sale.
Stephen, 45, from Manchester, says: "She is like any normal six-year-old, she doesn't let anything faze her. If you ask her what's wrong with her, she will tell you she needs a heart and lung transplant and she can't have one.
"She loves David and Victoria but prefers David because he is a man and he plays for Manchester United, which is her favourite team.
"Any event she goes to doesn't bother her. It doesn't matter who you are. When she met Prince Charles, she said "I've had enough of you, goodbye'. He just laughed and walked off."
Susie Mathis, who runs Kirsty's campaign, says: "From the first moment I met her, I knew she was very special. She surpasses every obstacle with such bravery and character.
"I am so proud of her and my dearest wish is for a miracle to enable her to lead a normal life. Her little face, beautiful eyes and truly inspirational story have touched our nation."