Hartnell has taken his Sydney form to Melbourne, cruising to victory in the Group One Turnbull Stakes.
The Godolphin-owned gelding has won three of his four starts this campaign by big margins with his only defeat his second to Winx in the Warwick Stakes.
Trainer John O'Shea says a decision on whether Hartnell tackles Winx again in the Cox Plate will be made in the next few days.