So You Think has been retired to stud in Australia.
The horse was found to be lame after exercise yesterday morning.
In a statement yesterday, managing owner Coolmore said the horse had pulled a muscle in his hind quarter ruling him out of the Eclipse Stakes tomorrow, which was set to be his last race.
So You Think won two Cox Plates with Australian trainer Bart Cummins before Coolmore bought the controlling stake in 2010.
Irish trainer Aidan O’Brien subsequently moved the horse to his Tipperary base.
“So You Think is an extraordinary horse and it was a real privilege to have had him here at Ballydoyle on loan from Australia,” said Aidan O’Brien.
So You Think won the last five of his 10 Group Ones and saw off the Queen’s Carlton House to win at Royal Ascot last month.
“It’s a big disappointment that he’ll miss the Eclipse, but he’s had a wonderful racing career and now it’s time for him to shine at stud,” said Coolmore Australia’s Tom Magnier.
“His book reads like a who’s who of all the best mares and breeders so he’ll get the best possible start.”
He will enter quarantine tomorrow as originally planned and will stand at Coolmore Australia for a $66,000 fee.