Reigning champion De Sousa had been odds-on to retain his crown and was well-supported on Tuesday despite only holding a narrow lead over Moore and James Doyle.

Moore last rode at Deauville on Sunday but has not had any mounts so far this week.

Aidan O'Brien believes Moore has been suffering from a hip problem.

The Ballydoyle trainer intends to speak to the jockey ahead of the expected appearance of Coventry Stakes winner Caravaggio in the Keeneland Phoenix Stakes.

"I wasn't talking to him and I haven't heard what has happened," he said.

"He was having trouble with a hip, I knew that the last while and you could see he was lame while he was walking but I wasn't speaking to him since.

"I'll speak to Ryan before making a decision on who rides Caravaggio - the plan is to run him."

David Williams of Ladbrokes said: "In what is rarely a busy market we saw elevated interest in bets coming through on Silvestre de Sousa.

"It quickly became evident that some punters were looking to back him at any price and the prudent thing to do in those circumstances and on a market like this is to take a breather."

When contacted Moore's agent Tony Hind said: "All I know is Ryan is having a holiday with his family.

"I spoke to Ryan on Saturday and he is off to Portugal on holiday and he said he'll speak to me when he gets back."

Moore's father, trainer Gary Moore, said: "I've not spoken to him, but all I know is he has gone away on holiday.

"Jamie (Moore) is on holiday as well, but I don't think they have gone together."