Blue Diamond Stakes contender Thurlow will figure in a gear switch for the $1 million race.

Blinkers will be replaced by a visor when Thurlow lines up in Melbourne's premier two-year-old event at Caulfield on February 28.

Trainer Robert Smerdon and jockey Craig Williams decided on a gear switch after the filly won a Sandown 800-metre jump-out on Tuesday morning.

Thurlow wore winkers at her first two starts which included a win over Miss Gidget at Sandown in November before blinkers were added when successful in the Chairman's Stakes on February 7.

Smerdon called for blinkers after a below-par barrier trial at Cranbourne and said the headgear had sparked the filly in a gallop before her last-start victory.

He is concerned the rise to 1200m on Saturday week in Group One company may result in the filly wanting to over-race.

"Going to the 1200 (metres) I put it all back on Craig and we'll go back to visors, which are modified blinkers and have peripheral vision," Smerdon said.

"She's thrived since her win, the jump-out was good, her action was good and she's earned her place in the field.

Smerdon said Miss Gidget, which finished second to Fontiton at Caulfield last Saturday, had franked the form of Thurlow, so far the second highest money earner leading into next month's Golden Slipper.

Trainer wants a wet Golden Slipper to test his filly.

"What I would be keen to see is, and it might happen in Sydney, is a wet track as the Sebrings seem to love it," Smerdon said.

"She's a lighter-framed horse and you'd expect her to get through ground like that."

Meanwhile Fontiton has come through her Blue Diamond Prelude victory in good order and Smerdon said she was likely to have a course proper gallop at Caulfield next week to top her off for the Blue Diamond.

"We probably just do some slow work and some swimming apart from the one gallop," Smerdon said.

"It's easy to train them hard but it's hard to train them easy."