Craig Williams has been skipping breakfast for a lightweight ride in a Group One race at Rosehill.

He is dieting to ride Griante at 51kg in Saturday's Group One Galaxy but it could all be in vain unless there are scratchings from the 1100m scamper.

If Griante fails to make the 14-horse field, Williams will be afforded the luxury of breakfast and a switch to another mare in Lumosty.

Both are $21 chances in a market headed by the Gai Waterhouse-trained English at $4.

Griante was an unlucky runner at her last start in a another Group One handicap sprint, the Oakleigh Plate, when finishing 12th.

"My manager targeted her after her run in the Oakleigh Plate and that form has been franked with The Quarterback winning (last week's) Newmarket," Williams said.

"She's got no weight, she's flying, she's got a great barrier draw, she has won in Sydney before and she loves soft ground, but unfortunately she's second emergency.

"I think she's a great chance if she gets in."

Williams galloped Griante between races at Moonee Valley on Monday and said she was in terrific order ahead of her trip to Sydney.

If she fails to gain a start in the Galaxy she will contest the Birthday Card Stakes with Hugh Bowman aboard.

Williams' back-up Galaxy ride Lumosty is raced by the same connections as Anatina who finished second behind Tiger Tees in the 2013 edition.

"She's a lightly raced but highly talented sprinting mare," Williams said.

"I think she's a better racehorse than the mare I ran second on behind Tiger Tees a few years ago.

"She's definitely credentialled enough to go there and for them to continue on that path they're obviously extremely happy with her."