New scans have revealed that the injury to Pat Cummins' back has not healed, leaving the Aussie skipper virtually no chance of playing in the first Ashes Test - and bringing his ability to play in any of the matches into question.
Sources have revealed that Cummins had more scans on his back last week which revealed his back stress problem had not improved as quickly as hoped.
It's believed Cummins is no chance of taking part in the series opener in Perth on November 21, and there are fears he may miss the entire five-Test series.
Steve Smith would likely be stand-in skipper while Cummins is on the sidelines.
Cummins, 32, had a scan last week to see how his recovery was progressing and was told that the stress 'hot spot' was healing but had not cleared up enough for him to bowl.
Given the Ashes series only runs for 49 days, Cummins is facing an uphill battle to get back and get fit in time for even the last two Tests.
It would be a shattering blow for Australia to lose their best bowler and skipper despite his likely replacement, Scott Boland, being a revelation at Test level in his limited opportunities.
He'll join Josh Hazlewood and Mitchell Starc as the pace battery in Perth, with Nathan Lyon to bowl his finger spin.
Aussie skipper Pat Cummins looks set to miss the start of the Ashes series
Cummins (pictured with wife Becky and son Albie) may miss the whole series given he still can't bowl due to back stress
While Cummins has been able to continue gym work and cycling, he hasn't been able to bowl or run.
Australia has held the Ashes since 2018 and is still favourite to win the series ($1.63) against England ($3.10), who have not won a Test in Australia since 2011.
When asked about missing the series a month ago, Cummings said: 'That would be devastating.'
'We'll be doing everything we can to be right for that, [and] make a few decisions a little bit closer, but [I'm] confident we'll do the rehab right and give it a good crack,' Cummins said.
'This far out it's hard to know, but we're trying to make sure we're doing everything right to be right for Perth. It's a big Ashes series, [it] doesn't get much bigger, so you're willing to be aggressive and take a few risks to try to play as much of the Tests as you can.'
The Daily Mail has contacted Cricket Australia for comment.