Scottish has suffered a recurrence of an old fetlock injury and is ruled out of Saturday's G1 Arlington Million in Chicago.
Trainer Charlie Appleby said plans to return to Melbourne with the globetrotting Godolphin star later in the year had also been scrapped.
Scottish finished a gutsy second to Jameka in last year's G1 Caulfield Cup and was also one of eight international invitees for the G1 Cox Plate at Moonee Valley on October 28.
"It's a real blow," Appleby said from his Newmarket (UK) base. "He had been working really well since returning from Royal Ascot in June, and the trip to the States was very much a prelude to spending the Australian Spring in Melbourne.
"But that's all off the agenda now. The good news is that long-term the prognosis is good. All going well, he should be right to race again early next year in Dubai.
"It is his near-fore, the same leg that caused him to miss the G1 Mackinnon at Flemington last November. He breezed at Arlington this morning (Thursday) and was found to be lame when he cooled down," the trainer reported.