Glenn Maxwell could be handed a Test reprieve if David Warner is not fit for the first Test, with the Victorian called up into the Ashes squad as cover.
Warner hurt his neck during a fielding session on Tuesday, and has declared he will be okay to play despite limited training since.
But the selectors have called up Maxwell, who was omitted from the 13-man squad, as back-up in the event Warner is ruled out of the first Test.
In the event he is not passed fit, Shaun Marsh would likely move up the order to open with fellow WA opener Cameron Bancroft, while Maxwell would reclaim his spot at number six.
Previous opening batsman Matt Renshaw may have been ruled out of contention with him named in Queensland's Sheffield Shield squad that was flying to Perth on Wednesday.
Australian skipper Steve Smith said Warner should be okay to play tomorrow.
"He said he'll even bat like Shivnarine Chanderpaul if he has to and face the other way, so I think he'll be alright," he told reporters.
"It's improved a fair bit over the last 24 hours. Hopefully he can keep improving and he'll be 100 per cent come 10 o'clock in the morning."
David Warner, Cameron Bancroft, Usman Khawaja, Steve Smith (c), Peter Handscomb, Shaun Marsh, Tim Paine, Mitchell Starc, Pat Cummins, Nathan Lyon, Josh Hazlewood