Blue Diamond favouritism will be decided when a host of talented fillies clash in their division of the Preludes at Caulfield on Saturday.

Fontiton and Secret Agenda headline a field of 14 for the fillies Blue Diamond Prelude (1100m) and sit on the top two lines of Blue Diamond betting.

The fillies Prelude also includes impressive Moonee Valley debut winner Heatherly, the Gai Waterhouse-trained Flamboyant Lass and Godolphin duo Antelucan and Pursuits.

Fontiton has been at the head of Blue Diamond betting since markets opened and remained there after she resumed in the fillies Preview at Sandown and chased down Haybah.

She has drawn barrier nine on Saturday while Secret Agenda has gate four.

"The barrier is a little bit sticky," Fontiton's trainer Robert Smerdon said.

Smerdon has been experimenting with teaching Fontiton to take a sit but admitted she would likely press forward from her draw.

"She's a filly that doesn't have to lead, but will probably press forward anyway," Smerdon said.

Fontiton galloped with three-year-old Eloping at Sandown last Saturday, and clocked smart time in a sharp hit-out.

The colts and geldings Prelude on Saturday has a field of 16 plus one emergency with Debutant Stakes winner Of The Brave drawing barrier 10.

He is on the third line of Blue Diamond betting at $8 with his opposition on Saturday including the Peter and Paul Snowden-trained colt Pride Of Dubai who will be out prove he is worthy of a late entry into the Blue Diamond.