Sir Percy has been ruled out of Sunday's Prix de l'Arc de Triomphe after a minor setback in training.
Sir Percy was a first Derby winner for trainer Marcus Tregoning
Marcus Tregoning's star has not raced since winning the Vodafone Derby by a short head from Dragon Dancer in June.
Tregoning said: "We will not be running in the Arc. We have decided against it as he has niggled a shoulder muscle on his off-fore shoulder."
"I don't think it's anything too serious - it just won't come right quick enough."
Tregoning is now hoping Sir Percy will recover in time to tackle the Emirates Airline Champion Stakes at Newmarket on 14 October.
"We will aim for the Champion now and hopefully he will be in good shape by then," he added.
"It's just one of those annoying things. The horse has been in great form but he's just basically sprained a muscle.
"We don't want to rush him back so we will looks towards Newmarket."
Sir Percy had been a general 14-1 chance for Sunday's 12-furlong showpiece.
Live coverage of the Prix de l'Arc de Triomphe meeting will feature in Grandstand on BBC Two from 1420 BST on Sunday.