The Lion In Winter has died after sustaining a fracture on the gallops at Ballydoyle.
The 4-year-old colt was last seen finishing fifth in the Lockinge Stakes (G1) May 16 and was being aimed at the Queen Anne Stakes (G1) at Royal Ascot June 16.
Aidan O'Brien said: "He got a fracture and, unfortunately, we just weren't able to save him. He was obviously a very good 2-year-old and it's a pity he never really got to fulfill that early potential. On his day he was very talented.''
The Lion In Winter won both his starts at 2, including the 2024 Acomb Stakes (G3), and was once considered the best of last year's 3-year-old crop. He was sent off the 8-11 favorite for the Dante Stakes (G2) on his 3-year-old reappearance but could only finish sixth behind Pride of Arras.
At one time he was favorite for the Epsom Derby (G1) and while he could only finish 14th behind stablemate Lambourn at Epsom, he went some way to repairing his reputation when dropped in trip, finishing placed in the Prix Jean Prat (G1), Prix du Moulin (G1), Queen Elizabeth II Stakes (G1), and Breeders' Cup Mile (G1T). He finished 12th in the Hong Kong Mile (G1) at Sha Tin Racecourse in December on his final outing last year.
There was hope he could improve as a 4-year-old and he returned with a smooth victory in the Heritage Stakes at Leopardstown Racecourse in April, although he struggled to build on that effort behind Notable Speech on what proved his final start at Newbury.
The son of Sea The Stars won three of his 12 races and earned more than £640,000 in prize money for his Coolmore owners Derrick Smith, Michael Tabor, and Mrs. John Magnier.
