Peter Snowden is looking forward to testing the carnival waters with King Of Roseau.

A clash with high profile colts Storm Boy and Gatsby's awaits King Of Roseau in the San Domenico Stakes and trainer Peter Snowden believes his charge can prove a thorn in their sides.

The son of Capitalist was only a length or two off some of the better juveniles in the autumn, finishing fourth to Prost in the Canonbury Stakes (1100m) and fifth to Dublin Down in the Pago Pago Stakes (1200m) before a narrow second to Arabian Summer in the Magic Millions National 2YO Classic (1050m) at Doomben in May.

Snowden says King Of Roseau has furnished beautifully as a spring three-year-old and he won't be surprised to see him run boldly at Rosehill.

"He's a really nice horse and I thought he did some good things, especially in Brisbane," Snowden said.

"He ran out of his skin there in the $1 million race when he got beaten a short half-head.

"He is taking on the A-graders on Saturday so it's a big ask, but the horse, he won't let you down and I think he'll be competitive here and run some sort of race from that good draw.

"You've got Gatsby's and Storm Boy, they're the two better colts around at the moment, so we'll get an idea where we sit on Saturday."

Tyler Schiller has the ride on King Of Roseau from barrier five, while Zac Lloyd will handle barn mate Zarrose in the Merrylands RSL Handicap (1500m).

The latter is chasing a hat-trick of wins and produced a devastating turn of foot to score at Randwick last time out.

If she can back up that performance this weekend, Snowden will consider a start in the Group 3 Tibbie Stakes (1400m) at Newcastle on September 20 for the emerging mare.

"She's got a great turn of foot, we saw that last start and hopefully we see it again on Saturday," he said.

"If she runs well, I might even look at the Tibbie with her at her next start after Saturday.

"I thought early says she might be a stayer, but keeping her fresh and spacing her runs, she is reacting really well to that."