Tony McEvoy is already a Cox Plate-winning trainer and will have three-year-old colt Royal Symphony in this year's race against champion Winx.
Steven Pateman and Belinda Dunn have been informed of high cobalt readings returned by horses in their care.
Last-start Queensland Guineas winner Salsonic will begin a campaign aimed at the Group Two Villiers Stakes when he runs in the Filante Handicap at Randwick.
Trainer Matt Cumani is hoping Grey Lion can finally get his first win in Australia in the Geelong Cup.
Trainer Kris Lees has decided to miss the Cox Plate with Sense Of Occasion and aim at the Kennedy Mile at Flemington.