As much as John O'Shea is excited about White Sage's return to racing, her reappearance as favourite has him totally confused.

White Sage will put an unbeaten record on the line in the NSW Thoroughbred Breeders' Classic at Rosehill on Saturday.

She is a firm top pick at $2.70 ahead of Catkins and Streama to make it six wins from as many starts but it's a market order that puzzles O'Shea.

"Have a look at the form of Streama, especially her form in the spring," O'Shea said.

"She was second in a Warwick Stakes, won a George Main (Stakes) and she finished second in an Epsom behind Boban.

"How is she not favourite?"

White Sage's best win was her most recent when she overcame a wide gate for jockey James McDonald to win the Festival Stakes at Rosehill in November.

It gave White Sage an important stakes success but it's status as an off-season Listed race is a long way removed in class from Streama's Group One George Main Stakes triumph in the middle of the Sydney spring carnival.

O'Shea is hoping White Sage can make a transition to Group One racing by the time the $600,000 Coolmore Classic is run at Rosehill on March 22.

"I'm not saying I don't like her (chances) or she's not a good mare but if you look at it objectively the betting market is not right," he said.

"I think she'll run very well and we're going to find out where we are at in the scheme of things on Saturday.

"Going off the ratings we will be getting seven kilos off those good mares in the Coolmore and that's where we can really make a mark."

O'Shea is going for a hat-trick of wins in the Group Two race restricted to mares.

He prepared Steps In Time for victories in 2012 and 2013 but she resumes on Saturday under the care of Joe Pride.

Her old trainer is well aware of how much of a threat she will pose to White Sage.

"Steps In Time is a much better horse in the autumn than she is in the spring," O'Shea said.

Streama will contest the Classic after trainer Guy Walter decided to dodge the out-and-out speedsters, including the O'Shea-trained Bernabeu, in the Lightning Stakes at Flemington.