Champion jockey Damien Oliver has been called up to replace Hugh Bowman on the John Moore-trained Ruthven in the Hong Kong Derby at Sha Tin.

Bowman had to relinquish his scheduled rides in Sydney on Saturday and Hong Kong on Sunday as he needs more time to recover from a fall from two-year-old colt Performer at Randwick last Saturday.

Bowman, who is the regular jockey of champion mare Winx, saw a neurosurgeon on Wednesday morning and was not cleared to ride this weekend and will have another appointment next week.

Told that Bowman was not able to ride Ruthven in the Derby, Moore was granted approval from the Hong Kong Jockey Club for Oliver to take the mount.

Ruthven won over 1800m in his most recent start in Hong Kong and Oliver said he was excited about the horse's chances.

"He's a quality horse and a last-start winner," Oliver said.

"It's obviously going to be a tough race to win but I've had a bit of luck with John in the past, so it's nice to get the call up from him.

"It's unfortunate for Hughie, but luckily he's OK and he'll get back to ride the mare (Winx)."

Winx is scheduled to have her next start on Saturday week in the Group One George Ryder Stakes on Golden Slipper day at Rosehill.

Bowman won last year's Group One Queensland Derby on Ruthven when he was trained in Australia by Ciaron Maher.