Massive outsider Diore Lia is out of the Investec Derby at Epsom.
Trainer John Jenkins was forced to withdraw the filly from the premier Classic after she pulled a muscle.
The daughter of Yeats had been a controversial runner in the Derby after she was well beaten on two racecourse starts this season.
She was initially due to have been partnered by 7lb claimer Gina Mangan, but the British Horseracing Authority blocked her from riding due to a lack of experience.
Paddy Pilley was instead set to ride before Diore Lia's enforced absence.
Owner Mary Todd's brother Richard Aylward bred the horse and had been keen to generate publicity for Great Ormond Street Children's Hospital by running the filly on the biggest stage of Flat racing.
Aylward said: "The filly was walking around the yard and they found that she was lame.
"The vets wouldn't have passed her to run and that was that.
"After all that hard work, I'm absolutely heartbroken.
"She wouldn't have come last as she was improving, but we'll just step back and have a think about what we do next.
"I'm absolutely gutted. Apart from my mother dying, this is the next-worst feeling I've had in my life."