Bryce Heys is certain his foresight in finding a jockey to match the occasion makes Randwick Guineas outsider Sworn To Silence a worthy runner in the $600,000 race.

Sworn To Silence is the least experienced of the six three-year-olds left standing in the Guineas and Heys will be putting the saddle on his first Group One starter.

Even allowing for Sworn To Silence emerging from the Hobartville Stakes as a horse of the future, his Guineas task would still appear a monumental one against Hallowed Crown, Shooting To Win and Sweynesse.

Heys sees it differently thanks to the booking of Zac Purton, the Australian jockey who last year ended Douglas Whyte's run of Hong Kong premiership wins.

"We've had this race in the back of our mind since he won his maiden at Wyong last year (in November)," Heys said.

"And I engaged the jockey quite some months ago to hopefully get to the race and he is the right man for the job."

Sworn To Silence ran the eye-catching race among the unfancied horses in the Hobartville, finding the winning post in a manner which points to him being at home over the Randwick mile course on Saturday.

"If we get the first half mile right I'm sure the horse will run the last half mile really, really strongly," Heys said.

"I think he's tailor-made to a mile on a big track and I'm not resigned to the fact he wants further yet even though he is racing like that."

The Guineas field was reduced to six runners on Friday when Scissor Kick was scratched due to a virus.

Scissor Kick's withdrawal ensured equal favourites Hallowed Crown and Shooting To Win tightened from their overnight quote to $2.60.

It also left Godolphin colt Sweynesse ($3.60) rated as the only serious threat to either colt adding another Group One to their record.

Racing manager Jason Walsh said Sweynesse's Hobartville placing raised hopes in the Godolphin stable he could be a Group One winner during the autumn.

"The Hobartville run probably exceeded our expectations," he said.

Trainer Chris Waller expects Victoria Derby winner Preferment to finish closer than he did in the Hobartville as the colt heads towards the ATC Australian Derby.

"It will be nice to see him beat a couple home on Saturday and then finish in the first three in the Rosehill Guineas," Waller said.