Black Panther owner Michael Owen and trainer Tom Dascombe have decided to replace jockey Richard Kingscote with Kieren Fallon for the St Ledger at Doncaster on Saturday afternoon.
Kingscote was wearing Owen's blue silks in June when he guided Black Panther to King George V Handicap victory at Royal Ascot.
However, Kingscote's win did not guarantee him the St Ledger ride and he has been switched with 46-year-old Fallon.
"I have spoken to Michael at length and it was a tough decision, but on this occasion we've decided to go for a more experienced jockey," said Dascombe.
"Richard has always done a good job, but you don't get too many chances to win a Classic and I decided that it was a decision that had to be made."
Black Panther is rated 10-1 with the majority of bookmakers to win the race.