Three quick wickets boost Australia
England were in danger of squandering their hard-earned advantage in the fourth Ashes Test after losing three wickets for one run on the third afternoon at the MCG.
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 against Mitchell Johnson - as a fielder as well as bowler this time - as they stumbled to 115 for four at tea.
Alastair Cook (51) 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 Nathan 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 when he reached a 60-ball fifty 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 kickstarted England's 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, 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.
Australia's wicketkeeper-batsman Haddin had earlier passed 50 for the fifth time in a series the hosts lead 3-0, with the Ashes urn in the bag already.
Haddin and Lyon punctured some of England's mid-match momentum, keeping them out in the field for almost threequarters-of-an-hour of a glorious morning.
There were six fours and a six in Haddin's two-hour half-century, from 59 balls - and Lyon was no silent partner either, mixing in some useful shots and assured defence between the inevitable plays and misses from a number 11.
Finally, though, the short ball worked for James Anderson (four for 67) when he had top-scorer Haddin pulling out of a hook and looping a simple catch to his opposite number Jonny Bairstow.