St Leger hero Encke has had to be put down after suffering a fatal injury during routine exercise.
The five-year-old denied Camelot the historic Triple Crown when claiming the season's final Classic at Doncaster in 2012, but missed the entire season the following year after being caught up in the Mahmood Al Zarooni drugs scandal.
He has returned this summer for trainer Charlie Appleby, running well in defeat in the Glorious Stakes at Goodwood, finishing third in the Irish St Leger and third in the Cumberland Lodge Stakes at Ascot earlier this month.
Appleby revealed on the Godolphin website Encke had sustained a hind leg injury and following complications, could not be saved.
The trainer told www.godolphin.com: "His Highness Sheikh Mohammed is deeply saddened at the loss of his Classic winner.
"Encke was a talented racehorse and will be sorely missed as he was one of the yard's favourites."
