American star California Chrome has been officially ruled out of the Prince of Wales's Stakes at Royal Ascot with a hoof injury.

Last year's Kentucky Derby and Preakness Stakes winner was reported to be sore on Monday morning and trainer Art Sherman has now withdrawn him from his Group One engagement on Wednesday.

The four-year-old has been stabled with Newmarket trainer Rae Guest, who said the injury was minor.

"He's been X-rayed and there's no damage, there's just a bit of pus and it will take a few days to come right," Guest said.

"It's just a minor thing but it's very disappointing.

"The main thing is that it's not life-threatening or anything. It could be much worse for the horse and while it's disappointing for us, the key thing is that the horse is OK."

Australian triple Group One winner Criterion is at 10-1 in the Prince Of Wales's Stakes.