Breeding isn't an exact science but trainer Gerald Ryan is hoping one of the traits Charlie Boy has inherited is ability on a wet track.

The early favourite for Saturday's Silver Slipper at Rosehill, Charlie Boy is by first-season sire Myboycharlie, a three-time winner in France on soft and heavy tracks.

Rosehill will be heavy after constant rain in Sydney since Thursday afternoon and Ryan has withdrawn Flying Snitzel from the Millie Fox Stakes.

"I think Charlie Boy will handle it but you never know. Some do, some don't," Ryan said.

"Everyone says the Snitzels are wet trackers but not all of them are.

"You can't always tell.

"Flying Snitzel doesn't like it and she will go to Melbourne for the Kewney Stakes next week instead of Rosehill."

Ryan has had more success than most with the progeny of Snitzel who he trained to win the 2006 Oakleigh Plate.

Myboycharlie is new to the scene but the Vinery stallion has created an impression with his first crop.

Charlie Boy's debut win in November gave him his first Australian winner and his most recent winner, Charles In Charge, ploughed through the heavy 8 ground at Sandown on Wednesday.

Myboycharlie won his first three starts, all on wet ground, with his Prix Mornay victory the highlight and the one which guaranteed him the title of France's champion two-year-old.

Charlie Boy, who is raced by Triple Crown syndications, has also been specked in early betting for the $3.5 million Golden Slipper on April 6.

The winner of the Silver Slipper (1100m) automatically qualifies for a start in the juvenile showpiece.

Ryan's other runner at Rosehill is Villa Splendido in the Fireball Quality (1100m).

"She will be running and I'm hoping she can get through the ground," he said.

"She hasn't raced on it before but she's by Holy Roman Emperor out of a Zabeel mare.

"I have a feeling she will get through it OK but once again you never can tell."

AAP TURF cw/wb