Golden Slipper dreams will go on the line at Rosehill on Saturday with a host of juveniles striving to stake their claims for a start in the world's richest race for two-year-olds.

The Gerald Ryan-trained Charlie Boy is the early $3.70 favourite for Saturday's Silver Slipper and has already had support from his opening quote of $3.90.

He is also the most prominent of the colts and geldings in Golden Slipper betting at $15 and that price will firm if he scores at Rosehill.

Charlie Boy was an impressive winner of his only start at the same track and trip in November and looked good taking out a recent barrier trial with race jockey Glyn Schofield aboard.

"Without a doubt he feels like a horse with a lot of ability," Schofield said.

"At his debut, he was green and he didn't really know how to get to the line.

"He seems to have learned. His trial was nice and he's going well."

Also prominent in Silver Slipper markets is the Anthony Cummings-trained Never Can Tell ($5.50).

The colt claimed a high-profile scalp when he defeated short-priced favourite and Breeders' Plate winner Whittington in the Canonbury Stakes last time out.

It was his second win from as many starts but at $26 for the Golden Slipper, he continues to fly under the radar.

Jockey Peter Robl says Saturday will be a true test for the youngster.

"He's going well and Saturday will give us more of a guide," Robl said.

"If he's not top shelf, well he's not far off them."

The Silver Slipper field has already been reduced to 12 runners with trainer David Payne scratching Criterion due to a wide gate.

He will instead run in the Black Opal Stakes at Canberra although Payne will still be represented in Saturday's race by Regimental Pride.

The Silver Slipper will also provide a crucial test of the strength of this year's Magic Millions.

Gai Waterhouse will run Sweet Idea who finished second in the Gold Coast feature and stable representative Mark Newnham warns punters not to forget her.

"She's underestimated. She was only just beaten in the Magic Millions and for the last few years the form from the race has been solid," he said.

The stable didn't accept with reigning Golden Slipper favourite Overreach who was among the original nominations.

"She will run in either the Reisling or the Sweet Embrace," Newnham said.

"She did a bit of steady work ... on the grass (on Tuesday) and she only needs one more run going into the Slipper."

The Golden Slipper will be run on April 6.