REUTERS: Frankie Dettori withdrew from Royal Ascot on Tuesday due to an arm injury suffered when he was thrown from a horse in the parade ring at Great Yarmouth last week.
Dettori was pencilled in for four rides on the opening day, including King's Stand Stakes favourite Lady Aurelia, who will now be ridden by John Velazquez.
"I've been trying so hard to get fit for today but had to accept this morning it wasn't going to happen," the 46-year-old said on Ascot Racecourse's Twitter account.
"I've got to have Physio and get it properly looked at so won't be at Ascot this week. For me that's soul destroying as it's the most important week of the year. I'll be counting the days until next year."
Italian Dettori has recorded 56 winners at Royal Ascot, the most among all active riders.
(Reporting by Simon Jennings in Bengaluru; Editing by Peter Rutherford)