Genetics is not an exact science and trainer Gerald Ryan will send Snitzerland out in the TJ Smith Stakes on a likely wet track hoping she throws to the paternal side of her family.

The Lightning Stakes winner has never run on a track rated worse than dead but Ryan is crossing his fingers her sire Snitzel's only performance on a heavy track is the guide.

Ryan prepared Snitzel for his 2006 success in the Group One Oakleigh Plate and has since trained many of his sons and daughters to feature wins.

"Some of them handle it, some of them don't," Ryan said.

"I don't know if Snitzerland will. She's never been on it.

"Maybe she will be like her father. She is fit and well and I thought her recent barrier trial was good.

"She will will run wet or dry."

The TJ Smith (1200m) is one of four Group One races on Saturday at Randwick which is rated in the heavy range with further showers predicted.

This year's Oakleigh Plate winner Lankan Rupee has been the dominant favourite since his Newmarket Handicap win in March.

He showed he was comfortable running clockwise with a win in a barrier trial last week in which Snitzerland finished fifth, 1-3/4 lengths behind.

The only time they have met in a race, Lankan Rupee beat Snitzerland by a nose when the mare made a late spring carnival appearance in a Listed race at Flemington after her campaign was interrupted by illness.

Ahead of Tuesday's declaration of final field and barriers, the Mick Price-trained Lankan Rupee is at $3.50 ahead of triple Group One winner Buffering at $6.

Irish visitor Gordon Lord Byron is at $8 alongside Zoustar with Snitzerland and Rebel Dane at $11.

The connections of Gordon Lord Byron chose the TJ Smith over the Doncaster Mile as the best option after the six-year-old made a late charge to win the Group One George Ryder Stakes (1500m).

Trainer Tom Hogan said with the potential of wet ground he preferred the shorter race.