Steven Arnold is one of the jockeys who could benefit most from Craig Williams' absence from the C F Orr Stakes meeting.

Williams failed in an appeal on Tuesday against the severity of a careless riding ban, meaning new riders needed to be found for a host of good chances at Caulfield on Saturday.

Arnold got the call-up to ride exciting juvenile Calliope in the Group Two Blue Diamond Prelude for fillies.

The Godolphin-owned, John O'Shea-trained filly is the $2.80 favourite to make a winning return in the Prelude (1100m), a key lead-up to the $1.5 million Blue Diamond (1200m) later this month.

"Obviously Craig was going to ride her on Saturday and I suppose it might have opened it up a bit for me because there was probably a few already locked in for other rides," Arnold said.

"It's obviously just a one-off but I'm rapt to be on her and hopefully she can win."

Calliope sits on the third line of Blue Diamond betting and impressed in her only start with her win in the Gimcrack Stakes in Sydney on October 3.

On that occasion Calliope overcame a slow start to score a comfortable win.

Arnold hasn't ridden Calliope but has watched her trial and the Gimcrack Stakes.

"She was impressive," he said.

"She missed the start badly which was a negative on that day but hopefully she'll step a bit better than that.

"She's had a jump-out down here and she seemed to step away well so that might have been a one-off.

"But on ability she looked good. She quickened well and put paid to them pretty quickly.

"I think they've got a pretty good opinion of her."

The fillies Prelude and the colts and geldings Prelude will provide a clearer picture to the Blue Diamond with a host of a contenders in action.

Calliope has barrier five in a field of 13 and is one of seven fillies unbeaten going into Saturday.

Others include Concealer, Sword Of Light and Zamzam.

A field of 16 has been declared for the colts has been declared with Defcon the early favourite.