The 2013 Derby winner Ruler Of The World has been retired and will start a breeding career in Ireland.
John Halley, a vet at trainer Aidan O'Brien's Ballydoyle racing stables, said: "He has a recurrence of the muscle injury in his hind quarters.
"He suffered it earlier in the summer and although it's not critical, we have advised that he be retired to stud,"
Ruler Of The World, a son of top stallion Galileo, won the Derby on just his third career start.
Coolmore Stud in Tipperary will now house six winners of the famous Epsom Classic, with Galileo, High Chaparral, Pour Moi, Camelot and Australia already there.