Magic Wand is out of the $5 million Cox Plate while her Aidan O'Brien-trained stablemate Armory has been passed fit to start.
The 2019 Mackinnon Stakes winner was scratched on Friday after failing to recover from a lameness issue affecting her off fore leg.
Armory had also been under an injury cloud but after undergoing a veterinary inspection, he was cleared to take his place in the elite field.
The withdrawal of Magic Wand has paved the way for Buckhurst, prepared by O'Brien's son Joseph, to gain a start.
The horse was controversially made an emergency when the Cox Plate field was declared on Tuesday but has earned a belated call-up with Jamie Kah to ride.