Trainer Chris Waller's concern about the mental attitude of Zoustar going into the Golden Rose has eased on the back of a carefully planned track gallop.

Waller revealed he put Zoustar against an inferior stablemate this week and the colt did what he was expected to do - win the gallop decisively and with a minimum of fuss.

The work was orchestrated to ensure Zoustar is in the right frame of mind for the biggest race of his career at Rosehill on Saturday.

"He was in a bit of a rough-house race first-up in the Run To The Rose and I don't like colts being in that situation," Waller said.

"I gave him a `kill' on Monday. We let a horse go four lengths in front of him that wasn't up to his standard and he picked him up easily.

"I thought it was good to give a colt a bit of confidence."

As it turned out, Waller might have been entitled to question his own mental wellbeing after Zoustar drew the widest in the 17-horse Group One field.

But the three-time premier trainer is matter-of-fact about the barrier because of his faith in Zoustar's jockey Jim Cassidy.

Cassidy won the Wyong Gold Cup on the Waller-trained Wazn last week, confirming the 50-year-old is still at the top of his game.

With Cassidy as irrepressible as ever, Waller is happy the split-second decisions in the $1 million race will be made by the veteran rider.

"We do a lot of homework on our form but we've got Jimmy Cassidy with 35 years of experience and that's hard to knock back," Waller said.

"He is as hungry as anyone and if he can save an inch here and there he'll be doing his best to do that."

Zoustar has lost favour with Golden Rose bookmakers and the BTC Sires' Produce Stakes winner is out to $13.

Victorian colts Prince Harada and Fast `N' Rocking have been the focus of most betting action since the barrier draw.

Prince Harada remains firm as a $4.20 favourite with Fast `N' Rocking at $6 while there has been support at longer odds for Sidestep, Cluster and Marseille Roulette.

Despite forecast showers for Friday and Saturday, 2mm of irrigation has gone onto Rosehill, bringing the total to 12mm for the week.