Michael Clarke has admitted that he's unsure when he'll return to cricket.
Where I sit right now is I don't know when I'll be back playing cricket. We have no idea how long it's going to take.
For a side struggling through its worst string of Test results in more than 100 years, it's a cruel blow. Yet it now seems that Clarke's ailing back is as fragile as his team's middle order, which begs the question: How would Australia fare if Clarke was forced to retire?
While it's not a question that Cricket Australia would like to contemplate as it prepares for this winter's return Ashes series, growing evidence suggests that Clarke's career is in danger of being cut short. Certainly, the semi-crouched positions Clarke must assume as both a batsman and slip fielder look increasingly less sustainable as the 32-year-old's troublesome back continues to hamper his tenure.
So just how would Australia fare in his absence? Let's break it down and examine the two areas where Clarke's departure would be most detrimental.
A team with precious-few elite performers can hardly afford to lose its sole world class act.
Undoubtedly, Australia's already vulnerable batting order would be left reeling if Clarke's reign was prematurely ended. While his talent is unmatched within Australia's ranks, it's the sheer weight of his contributions that really defines his impact on the team.
Clarke's tally of centuries is more than double that of his fellow top six combined, based on the lineup used in the team's most recent Test outing at The Oval in August. More worryingly, the team's second highest accumulator sits more than 4,000 runs adrift of the captain.
The immense volume of Clarke's efforts is impossibly difficult to replace, with the team's remaining incumbents unlikely to sufficiently overcome his absence.
In all likelihood, either Ed Cowan, Usman Khawaja or Phillip Hughes would be reinstated into the top order, perhaps shifting Shane Watson down to No. 4. While all have Test experience, none have convinced selectors over their long-term future, with the trio lingering around the fringes of the nation's best XI.
Conversely, the ever-improving, but hardly established Steve Smith, could be forced to make the jump to No. 4 in the order, leaving a vacancy one spot below for a player more suited to the middle order.
National Twenty20 captain, George Bailey, is putting together a strong case for Test consideration after a strong run of form dating back to the beginning of the ODI series in England. Bailey, who is currently deputising for Clarke in India, would also help to lessen the impact of the leadership vacuum created by Clarke's absence.
Other options for places in the middle order include Mark Cosgrove, Matthew Wade and Alex Doolan, but that's not exactly a roll call that inspires optimism when contemplating how to replace Clarke.
Verdict: Despite the improvement shown during the final three Tests of the Ashes, Australia's batting lineup would be in tatters if Clarke was forced to retire. In his absence, Australia's top six would be one of the worst units among the the major Test playing nations.
It's a damning reflection on Australian cricket that no obvious candidate exists to replace Clarke as captain.
The team's well documented off-field indiscretions are undoubtedly a result of the lack of genuine leaders within the current dressing room. Furthermore, it's plainly obvious that Clarke lacked supportive senior figures during the team's turbulent recent history.
In the current Test side, Brad Haddin is considered the next best leader, but at 35 years of age, time certainly isn't on the keeper's side. While Haddin could be used as a short-term replacement—somewhat of an interim captain—his appointment would leave selectors with the very same issue less than 12 months down the line.
Bailey, as previously mentioned, would also be in the selector's minds given that he's performed the role at various stages in the limited overs formats.
However, the seemingly volatile nature of Australia's dressing room unity could be easily disturbed by installing a Test captain who is yet to play a match under the baggy green cap.
Yet looking past Haddin and Bailey for captaincy candidates is as hard as finding technically gifted English midfielders.
Who would replace Michael Clarke as Test captain?
Among the batsman, Shane Watson is the only man to own any leadership experience at Test level, following his short-stint as Clarke's deputy. Chris Rogers hasn't been in the national setup long enough, Smith is too young, while David Warner is anything but captaincy material.
The candidates residing in the bowling ranks are also few and far between. The two most realistic options from the bowling crop are Peter Siddle and Ryan Harris, both respected figures in Australian cricket, yet neither possess the tactical nous, nor the public relations skills to excel as captain.
Verdict: Perhaps more worrying than the team's batting depth behind Clarke is the team's glaring lack of true leadership. If Clarke's career was prematurely cut short, Australia would be left without an obvious captain in the format that matters most.
It's not overstating the matter to suggest that Australia might enter a debilitating crisis if Clarke's career was tragically brought to an end as a result of his current back injury.
His sheer weight of runs, combined with his presence as the only genuine option for the captaincy, means that the 32-year-old is perhaps the most irreplaceable player in world cricket when you consider the desperately shallow depth that surrounds him in this current Australian generation.
Although it's too early to declare the end of Clarke's career, the mere thought of losing their captain must be a terrifying one for Cricket Australia.