Gai Waterhouse has strengthened her claims for a fifth Golden Slipper with Sweet Idea cementing her berth with victory at Rosehill on Saturday.

The runner-up in the Magic Millions in January, Sweet Idea ($6.50) stormed home to win the Group Two Silver Slipper (1100m) and gained automatic entry to the world's richest juvenile race.

Jim Cassidy had Sweet Idea third in the early part of the race as Kuroshio and All The Talk took off and at the head of the field.

Cassidy said the two were about four lengths in front at the 600 metres and maintained the margin into the straight.

Sweet Idea was in the best position to pounce but as she did, Whiskey Allround ($8.50) made his move on the inside.

The filly had a neck to spare over the Queenslander on the line with equal favourite Charlie Boy ($5.50) making late ground for third, another two lengths away.

All The Talk wound up fourth while Kuroshio finished sixth.

"She was impossible to beat today and she will be very hard to beat on Golden Slipper day," Waterhouse said.

"The fillies have it all over the colts this year."

The Waterhouse-trained filly Overreach is the $4.60 favourite for the $3.5 million Golden Slipper (1200m) on April 6 with another filly Villa Verde second pick at $8.

Charlie Boy and Sweet Idea both firmed to $15 after the Silver Slipper, run on a heavy track.

"She was going nowhere at the 600 (metres)," Cassidy said.

"Then she picked up and started coming. She'll improve a lot and this race will toughen her up."

The wet track took care of several hopes including Darley runner Citations.

"The race was over after the first 100 metres," jockey Christian Reith said.

The performance of Whiskey Allround was both encouraging and perplexing for Brisbane trainer Tony Gollan.

"He was a bit fractious and came out slowly which is not like him," Gollan said.

"We know he can handle the wet ground now but I'm not sure where that leaves us from a Slipper point of view.

"The owners have to pay a late entry fee to put him in the race and that's the key decision.

"He's booked on a float home on Monday and we'll think about whether to run him in Queensland or bring him back to Sydney."