A horse bought for speed but who turned out to be an above-average stayer could save jockey Craig Williams's Sydney autumn carnival.

By Williams's lofty standards, it's been a lean carnival.

One of Australia's most sought-after riders, Williams' carnival has fallen away after starting on a promising note with Criterion's Todman Stakes win.

But trainer Kerry Parker holds out hope he can deliver a belated Group One for the jockey who plies his trade around the globe.

Williams will ride Aliyana Tilde in the $500,000 Sydney Cup, a mount he picked up when Corey Brown decided to follow Snitzerland to Adelaide for the Robert Sangster Stakes.

"With Corey going to Adelaide it's worked out perfect getting a rider of the calibre of Craig," Parker said.

Aliyana Tilde is a $13 Sydney Cup chance ahead of Wednesday acceptances after finishing third in the Chairman's Quality.

By Snitzel, the winner of one of Australia's biggest sprints in the Oakleigh Plate, her place on the fifth line of betting is as deserved as it is unlikely.

"When I got her at the sales I thought I was buying a two-year-old," Parker said.

"But when I got her up and running I had to put her in the paddock because I thought she was an Oaks filly."

Parker was right because Aliyana Tilde was beaten narrowly by Streama in last year's Australian Oaks.

She has done nothing but confirm her profile as a genuine stayer ever since.

"She stepped up well in the Chairman's and she relaxes so well in her races I can't see why she won't step up again in the Sydney Cup," Parker said.

Parker flirted with a decent Sydney Cup result last year when Nextanix ran fourth to Niwot.

Nextanix subsequently bowed a tendon, leaving Parker with Aliyana Tilde as his Cup horse for 2013.

"In Nextanix's absence, Aliyana Tilde has really carried the flag well for the stable," he said.