MITCHELL Johnson's retirement has caught Australia un-awares ahead of the final trans-Tasman Test and exposed the alarming vulnerability of their fast-bowling depth.
New Zealand now have a genuine shot at returning home with a drawn series - their only assignment to win the first ever pink-ball Test in Adelaide next week. Such a result would serve as an unmitigated disaster for Australia given the way they dominated at the Gabba and grinded the Black Caps into the dust on day one in Perth.
Peter Siddle will be named in today's squad for the third Test, and James Pattinson is also a likely addition. But make no mistake, Johnson's withdrawal is a serious disruption to the balance of the attack. 
Looking ahead to   February's return tour of New Zealand, Australia are now one Mitchell Starc injury away from a fast-bowling crisis.
And as we know, the new left-arm spearhead is carrying an ankle problem that, though stable, could require surgery at any moment.
Usman Khawaja's untimely hamstring injury hasn't helped the equilibrium. Selectors are now deciding between the young Cameron Bancroft and Glenn Maxwell and the old Shaun Marsh and Michael Klinger as his replacement.
There's no question that Johnson is an all-time great who deserved to go out on his own terms.
But having one of your biggest stars pull the pin midway through a series is never ideal. Just think Graeme Swann walking away during the Johnson-dominated 2013-14 Ashes.
It would appear Johnson's shocker at the WACA Ground told him that he would only be holding Australia back by continuing in Adelaide. That might be so, and is noble if true, but it doesn't change the fact reserves are thin.
Australia thought they had Johnson committed for the summer. Now they face taking some serious risks in Adelaide, particularly with raw talents Hazlewood and Pattinson.
Ahead of this Perth Test, Steve Smith admitted that -Hazlewood's bowling loads were close to going into the red.
Thirty-two first-innings overs in scorching Perth heat on the flattest WACA wicket on record is hardly going to help Hazlewood. Even though he has plenty of time to recover ahead of next Friday's start in Adelaide, Hazlewood's chances of playing every Test this summer appear nil.
And given he's taken just four wickets this series at 68.25, Hazlewood's form is down as much as his body's current ability to cope.
Pattinson, like Hazlewood, is a potential superstar, but Cricket Australia was so worried about his loads it rested him from Victoria's second Sheffield Shield match of the season.
Having lost Pat Cummins for yet another season due to injury, Australia are exercising extreme caution at pushing Pattinson over the edge. He is a 25-year-old with his own long-running injury history.
A host of other good young bowlers around the country like Nathan Coulter-Nile and Jason Behrendorff are also making their way back from injuries.
Siddle will almost certainly play in Adelaide, and based on his one-and-only match of the Ashes series, still has plenty to offer at Test level.
However, if pitches remain as flat as they have been this summer, Siddle is going to have his work cut out taking wickets.Personnel is not going to be a problem when the West Indies roll into town. But save for Mitchell Starc - the pink-ball king - Australia could be under the pump to close out this series in Adelaide.