England dismissed for 179
England lost their last five wickets for six runs to be bowled out for 179 and set Australia 231 to take a 4-0 lead in the Ashes at the MCG.
Only captain Alastair Cook (51) and Kevin Pietersen - falling one short of his second half-century of the match - gave England anything worthwhile to bowl at, after they had taken a first-innings lead of 51 on day three.
Between the efforts of captain and senior batsman, England descended first from 86 for one to 87 for four and then terminally from 173 for five as Mitchell Johnson (three for 25) took his series tally past 30 wickets and Nathan Lyon (five for 50) reached 100 Test victims - only the sixth Australian off-spinner to do so.
All was uncannily well for the tourists, in this series where so little has been, as they added 65 for none to a first-innings lead of 51.
Yet again, though, they were to founder first of all against Johnson - as fielder as well as bowler this time.
Cook dominated the scoring in his opening stand with Michael Carberry, after Brad Haddin (65) had first piled a little more frustration on England as he and Lyon put on 40 for the last wicket in Australia's 204 all out.
Cook was then immediately fluent in England's second innings, either side of lunch.
But for Carberry, after an involuntary single first ball, there were 36 dots before a memorable back-foot boundary past cover off Shane Watson.
Cook had already become the sixth Englishman to pass 8,000 Test runs by the time he reached a 60-ball 50 with his seventh four, cut past point off Watson.
The return of Johnson eliminated the England captain, though, caught only half-forward to go lbw.
Aleem Dar soon made an instant call to send Carberry on his way too, gone again to a bowler operating round the wicket, when Peter Siddle ended his 81-ball struggle for just 12 runs - lbw on the back foot.
That was the moment which kick-started England's first wobble, Joe Root trying to scamper a single off Lyon wide of mid-off only to be run out by Johnson's athleticism and accuracy with a direct hit at one and a half stumps.
When Ian Bell then chipped his first ball from the off-spinner straight into the hands of Johnson in the same position, the tourists were in danger of imploding again on this tour which has exposed their vulnerabilities so often.
There was very nearly another self-inflicted blow too before tea, Pietersen escaping on nine only because Siddle missed the stumps from cover with the batsman well short of his ground responding to a faulty single for Ben Stokes.
Lyon had Stokes mistiming an attempted big hit to deep mid-off in early evening, but Michael Clarke then gave Jonny Bairstow a 21-run start before unleashing Johnson on him again.
The left-armer had made especially short work of the young Yorkshireman in the first innings, and Bairstow - who had twice struck Lyon for sixes down the ground - could not muster another run before edging a fast and full delivery behind to become Johnson's 30th victim of the campaign.
Johnson was fired up, bowling downwind as Pietersen stopped the game for a distraction behind the arm and then 40mph gusts kept blowing litter over the square.
It was to be Lyon, however, who would take the next two wickets in four balls - Tim Bresnan missing a pull and losing his off bail and then Stuart Broad edging to slip on the front foot.
Then when Pietersen got underneath an attempted big hit at Lyon to be caught at long-off, James Anderson and Monty Panesar could add no more runs before Johnson finished the job when he pinned England's number 11 lbw.
Haddin had earlier passed 50 for the fifth time in the series, having hit six fours and a six.
He and Lyon therefore punctured some of England's mid-match momentum, in a passage of play which lasted almost three quarters of an hour of a glorious morning before top-scorer Haddin tried to pull out of a hook at Anderson (four for 67) and looped a simple catch to wicketkeeper Bairstow.