Borderlescott will be out for the rest of the season after he injured himself at Goodwood on Thursday.
The eight-year-old sprinter will not be able to bid for a hat-trick of wins in the Coolmore Nunthorpe Stakes at York in August.
He will, instead, remain at Arundel Veterinary Centre to undergo a bone scan next week.
"They have not quite diagnosed what it is, but he's going to have a bone scan next Thursday. He's staying down at Arundel and he's in good hands," said trainer Robin Bastiman.
"It's something from the pelvis down. He might have chipped a bit of bone off, but we're not quite sure. That's why he's having a bone scan. It's his near hind quarters and he might just have torn a muscle.
"The vets say that the horse has overdone it. He's tried too hard and overstretched himself.
"It's not a life-threatening thing but he will be out for the season. He won't be able to run again this year. He'll have to win the Nunthorpe next year.
"Hopefully he'll be all right and I have a gut feeling he will be."