The absence of star colts Pierro and All Too Hard from the Randwick Guineas has thrown Saturday's Group One race open with Chris Waller to field two leading chances.

Pierro, winner of the Hobartville Stakes, will take on older horses in the Canterbury Stakes a week later while All Too Hard, who missed the Australian Guineas with a cold, is slated to return in the Phar Lap Stakes on the same day.

The Waller-trained Shoot Out snared his second Chipping Norton Stakes on Saturday to kick off autumn Group One racing in Sydney and his stablemates Sacred Falls and Tougher Than Ever will do battle in the Guineas (1600m) at Warwick Farm.

Both are Group One winners in New Zealand who joined Waller's team this year.

Sacred Falls suffered his first defeat when fifth in the Royal Sovereign Stakes (1200m) won by Guineas rival Rebel Dane.

Waller was still waiting to confirm a rider on Sunday with New Zealander Leith Innes, who has ridden the colt in all his seven starts, weighing up rides at the Oaks meeting in Auckland.

Sacred Falls was withdrawn from the Hobartville Stakes (1400m) won by Pierro on a heavy track on March 2 while Tougher Than Ever handled the wet a week earlier to run second against older horses in the Apollo Stakes.

"Tougher Than Ever trialled well on Tuesday and going back to his own age group will help," Waller said.

"Jim Cassidy will ride.

"Sacred Falls had a gallop between races at Canterbury on Friday night and I'm sure he will prefer it on top of the ground.

"I'm still not certain what Leith's commitments are in New Zealand. It's possible he will stay there for the Oaks."

Waller is well on the way to his third Sydney trainers' premiership and is established as a trainer of Group One winners.

But the Randwick Guineas counts as one that got away.

In 2008, Waller was a star on the rise and had his first genuine Group One contender in Triple Honour who was beaten a nose by Weekend Hussler in a deceptive photo finish to the Guineas.

Two starts later, Triple Honour earned himself pride of place in the stable when he beat Casino Prince to win the prestigious Doncaster Handicap.