Three-year-old colt Bivouac is the favourite ahead of nominations for the Group One Oakleigh Plate with three-year-old filly Anaheed another strong contender.
Trainer James Cummings believes Microphone's Australia Stakes performance indicated the colt would be better suited stepping up to 1400m in the Autumn Stakes.
Connections of three-year-old Microphone have opted to have to colt bypass the Listed Kensington Stakes and instead head to the Group Two Australia Stakes.