Four-time Group One winner Postponed has been retired after "suffering a stress fracture", trainer Roger Varian has announced.
Winner of the King George VI And Queen Elizabeth Stakes in 2015, when trained by Luca Cumani, the son of Dubawi joined Varian prior to the start of last season and enjoyed a stellar campaign.
The six-year-old kicked off his year with successive victories in Dubai before adding to his top-level tally in the Coronation Cup at Epsom and the Juddmonte International at York.
Although he was beaten into fifth when favourite for the Prix de l'Arc de Triomphe last October, owner Sheikh Mohammed Obaid Al Maktoum sportingly brought him back into training as a six-year-old, but injury has now curtailed a decorated career.
The Newmarket handler told www.varianstable.com: "P ostponed has been a magnificent racehorse to have in the yard and it has been both a pleasure and privilege to oversee the second phase of his career.
"I am very grateful to Sheikh Mohammed Obaid for allowing me that opportunity and to Postponed himself for proving such a willing and talented ally."
Postponed returned to Meydan earlier this year and filled the runner-up spot in the Dubai City Of Gold before taking third spot in defence of his Sheema Classic.
Varian said: "It's a shame for everyone that we won't see him on a racecourse again, and it's especially sad for Sheikh Mohammed Obaid, who showed such sportsmanship in keeping him in training.
"Postponed had all the attributes of the complete champion racehorse - the speed, the stamina, and a telling kick. He travelled like a machine.
"A stress fracture like this wouldn't usually be a career-ending injury - except that it's May and he's six, and we don't want to take unnecessary risks with him.
"He's done us all proud, and we owe him a great debt of gratitude."
A statement posted on Varian's website said that a decision on Postponed's future stud plans will be "taken at a later date".
Postponed won nine of his 20 races and earned connections just short of £5million in prize-money.
