Australian horse Criterion will need a new jockey when he has his next start in England with Chad Schofield unable to ride in the Juddmonte Stakes.

Schofield, who rode Criterion to fifth place in last month's Prince Of Wales's Stakes at Royal Ascot, had first refusal for the race on August 19.

But by the time the Juddmonte comes around, the 21-year-old Australian will be settling into the next phase of his career in Hong Kong.

Although the Hong Kong season does not start until September, jockeys are required ahead of time for trackwork and trials.

Craig Williams, who rode Criterion to win Sydney's richest race, the $4 million Queen Elizabeth Stakes in the autumn, missed the Royal Ascot ride when owner Sir Owen Glenn opted for fellow Australian Schofield.

Schofield has been spending the southern hemisphere winter in England gaining experience ahead of his Hong Kong stint.

Co-trainer David Hayes will take time out from a European holiday over the next couple of weeks to visit Criterion, the winner of three Australian Group One races.

Criterion is scheduled to return to Australia with the first shipment of overseas horses heading to the Melbourne spring carnival.