Bemused England had no explanation for the latest batting collapse to beset their Ashes campaign.
The tourists appeared well-set in the early afternoon on day three of the fourth Test to consolidate a hard-earned advantage at the MCG.
They took a lead of 51 runs into the second innings, and - thanks to Alastair Cook's half-century - were 65 without loss soon after lunch.
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But they lost all 10 wickets for another 114, three for just a single in the 80s and then their last five for six runs.
Jonny Bairstow's departure, after a stand of 42 with Kevin Pietersen, kickstarted the terminal decline as England managed to set Australia only 231 to win and go 4-0 up after all.
Mitchell Johnson (three for 25) was once more a driving force for Australia - and this time, Nathan Lyon took five for 50 and reached 100 Test wickets in his 29th match.
After Australia had then moved to 30 for none at stumps, Bairstow admitted the clatter of England wickets was baffling.
"I'm not really sure I can explain what happened - but it was disappointing," he said.
England's supporters could hardly be surprised at the turn of events, because it has been a recurring theme of the winter to see their team blown away by Johnson.
He was also wind-assisted here from the Members End, as 40mph gusts set in from the north and often stopped the match with litter on the square and the bails regularly out of their grooves - even when wickets were not falling.
Johnson, as in the first innings, was too good for Bairstow.
But the wicketkeeper-batsman refused to endorse the suggestion that the left-armer is, by head and shoulders, England's biggest problem.
"Any of their bowlers are bowling very well at the moment - it's not just one bloke that changes the game.
"Obviously today was an occasion when we were not quite good enough in that evening session."
As for the challenge of keeping Johnson at bay, he added: "It is like facing other guys around the world - it's not just him that bowls 150kph.
"It is obviously a good challenge and one that ... you do enjoy.
"To do that here in a Boxing Day Test is very enjoyable."
Sadly for Bairstow, and England, he did not do so for very long.
"If he came up against any other side in the world, other teams would struggle as well ... it is not just our batsmen," he added.
"Possibly the left-arm angle is something that may contribute to it.
"It's like (Lasith) Malinga - people take time to get used to different actions around the world - and bowling at 150kph is not going to be easy at the best of times."
Lyon was an able accomplice for Johnson, as England's last four batsmen mustered just a single between them.
"You have to play your natural game," said Bairstow.
"Another day, one goes past slip or hits a gap. Today it wasn't meant to be.
"Naturally it is disappointing not to score big runs.
"But we have what we have, and are still 200 runs in front.
"Tomorrow we have to concentrate on getting the job done and taking 10 wickets.
"We are very confident. We have people in our side who have shown the skills that are needed."
The odds appear to favour Australia on a pitch which has been awkward for most batsmen but is not expected to deteriorate significantly.
Certainly, Lyon does not believe it was responsible for England's struggles.
"That's a great Test match pitch - there's no point blaming the pitch for what's happened in the game," said the off-spinner.
"Our pace attack has been fantastic.
"It's probably up there with the best in the world right now. I'm lucky enough to be involved with them."
Australia were again also indebted to Brad Haddin, who passed 50 for the fifth time in the series from number seven - and shared a 40-run 10th-wicket stand with Lyon, much to England's frustration.
"Brad Haddin hands down has been probably the backbone of our batting," added Lyon.
"He's been fantastic since coming back into the side. He's a great leader and he's a great fighter."
As for the 201 runs still needed by Australia to keep a whitewash on the agenda in the final Test, Lyon said: "We're definitely confident we can get the job done, but we know it's going to be a tough challenge."