Australian captain Meg Lanning has left the door open for a shock selection call on Ashes eve while contenders line up to fill a vacant top-order spot.
Elyse Villani and Georgia Redmayne are among the options for Thursday's Twenty20 series opener against England after Beth Mooney had surgery on a broken jaw on Tuesday.
Mooney's absence - potentially for the entire series - is a huge blow for the world champions given her eight half centuries in the format across the last two years is more than the rest of the team combined.
But in a sign of the depth at Lanning's disposal, Australia will also contemplate leaving Ellyse Perry out of the side as they mull their many middle-order options.
While Perry remains a fixture in Australia's Test and ODI team, chief selector Shawn Flegler and Mott have indicated in the past week she is no guarantee to be in the T20 team.
Perry missed this week's warm-up games against Australia A after it emerged she had contracted COVID-19 earlier this month and only joined the squad on Tuesday.
"Ellyse arrived last night, later than expected but she's in the squad now and available for selection, so we've just got to see what our best line-up is and we'll find out tomorrow," Lanning said.
Australia's bowling depth passed the test in a tough series win over India last year.
"And this presents a bit of a test for our batting depth," Lanning said.
"It'll create an opportunity for someone and I'm looking forward to seeing what pans out."
Australia have a ready-made replacement in Haynes in their squad ready to open, but she appears likely to stay in the middle-order after batting there in warm-up matches against Australia A on Tuesday.
Instead, Redmayne and Villani loom as the most likely options to partner Alyssa Healy.
Redmayne is uncapped, but scored 29 and 18 in the two matches for the 'A' side in Tuesday's internal hit-out.
Villani meanwhile put on 47 from 42 and 45 off 27, after having not played for Australia since 2019.
She was dominant as the third leading run-scorer in this summer's WBBL with 439 at 43.9, while also topping the statistics in last season's WNCL.
Grace Harris could also loom as a left-field option.
"I think she ( Villani) played fantastic, and working in partnership with her was really special," Redmayne said.
"It's hard to know what they (the selectors) are going to do. They obviously have a lot of depth in the Ashes squad."
If selectors do opt to play Haynes in the middle order, it could come at the expense of the game's biggest name in Perry.
Haynes missed the most recent series against India, while allrounder Tahlia McGrath starred to create a squeeze in the middle-order.
