American star California Chrome appears certain to miss the Prince Of Wales's Stakes at Royal Ascot leaving Australian contender Criterion with eight rivals.

The Art Sherman-trained California Chrome won the first two legs of the US Triple Crown last year and finished second in the Dubai World Cup at his most recent start in March.

The four-year-old has been staying at the Newmarket base of trainer Rae Guest who said a foot abscess made it doubtful he would be ready to race by Wednesday (Thursday AEST).

"He is not ruled out yet, but he has a bruised foot. Unless it is OK in the morning, which is doubtful, he won't go to Ascot," Guest said.

"He has had a vet put a hole in to let any poison there might be out, but if he can't get a shoe on in the morning he won't run."

Free Eagle is the favourite for dual Melbourne Cup-winning trainer Dermot Weld.

Criterion, a 10-1 chance, will be ridden by Chad Schofield who got the nod over fellow Australians Craig Williams and Damien Oliver.

The 21-year-old Schofield has been gaining experience in England for the past few weeks and has ridden two winners there.

He also received the news on Monday he had been granted a five-month contract to ride in Hong Kong from September.

Jamie Spencer will ride second favourite The Grey Gatsby with Cox Plate and Melbourne Cup winning jockey Ryan Moore choosing Cannock Chase.