Stokes gives England stay of execution
England 251 and 5 for 251 (Stokes 72*, Bell 60) require another 253 runs to beat Australia 385 and 6 for 369 (Watson 103)
Scorecard and ball-by-ball details
It seems only a matter of time now. Australia slipped to within five wickets of regaining the Ashes on a day of free scoring and the occasional moment of terror caused by a WACA Ground pitch that is cracking up almost as comprehensively as England have done to find themselves in this position.
There was some faint consolation to be found for the tourists in the unaffected strokeplay of Ben Stokes but any day on which the spearhead of your bowling attack is taken for 28 runs from an over and your captain clean bowled first ball is not one for England to remember fondly. They plumbed considerable depths in the morning session, as Shane Watson then George Bailey battered the bowling senseless to allow Clarke to declare well before lunch.
Following Harris' first ball, Australia's bowling was not their best of the series, as the pacemen sought wickets with an impatience they have largely eschewed in favour of unrelenting pressure. Nonetheless, they did enough to bring the match to a juncture at which only something truly miraculous will prevent anything other than an Australian victory sometime on Tuesday. They may only require four more wickets - Stuart Broad's brief foray to the nets with a badly bruised foot did not appear promising.
Watson benefited from a situation in which he was free to play on instinct, depositing Swann into the stands with relish, crashing 37 runs from 13 balls he faced from England's No. 1 spinner. He enjoyed a moment of fortune when one straight hit was caught by Tim Bresnan, only for the fielder to tumble over the long off boundary. Watson's departure was a comic masterpiece, skying a pull shot that Ian Bell dropped, but then run out as the annoyed bowler Bresnan threw down the stumps with Watson wandering out of his ground oblivious to the danger.
Bailey equalled the record for the most runs scored in a Test over from Anderson, allowing Michael Clarke to declare the at the psychologically numbing moment a third straight six of the over had crashed into the sightscreen beyond the boundary.
Left with a handful of overs to face before lunch, the bedraggled tourists reeled from the loss of Alastair Cook to a wondrous first delivery of the innings from Ryan Harris that shaped in then held its line to pluck the off bail. Joe Root and Michael Carberry did well to survive to the interval.
Resuming with an enormous task ahead simply to get through to stumps, Carberry and Root aimed mainly to survive. Clarke shuffled his bowlers around, and Watson struck, confounding Carberry from around the wicket just as Harris did in the first innings. The ball was full, shaped in a touch to beat the inside edge and would have crashed into the stumps.
Pietersen pushed his first ball from Watson down the ground for four, and looked comfortable enough as he survived an initial burst from his nemesis Peter Siddle. Clarke called on Johnson from the River End, and one ball angling across Root drew a loose flirt and an edge wonderfully taken by Haddin. Root hit the ground at the same time as the ball and immediately reviewed. His sense of injustice was mitigated by replays showing a clear edge, leaving Bell and Pietersen to scrape their way to tea.
Needing seven wickets in the session to claim victory and the Ashes, Australia's eagerness was manifested in some of their more impatient bowling of the series. Pietersen played breezily, advancing to loft Lyon into the Lillee-Marsh Stand and looking for a moment like he was capable of anything. But Clarke's choice of ends for Lyon was intelligent, coaxing Pietersen to hit into the breeze, and his next attempt held up. Harris, with an eternity to settle under the chance, held it safely.
That wicket might on another day have opened the floodgates, but Bell and Stokes responded to a seemingly hopeless situation with admirable verve. For the first time in this series Harris was hit out of the attack, while runs accrued rapidly enough to give the Barmy Army some reason to sing other than their own fortitude. Stokes was particularly fluent, driving ramrod straight and pulling with certainty.
Bell was organised and elegant as ever, prospering with several uppercuts over the slips. But it was with one such effort that he gave up his wicket, Siddle striking as the shadows grew long. The edge was audible, but the umpire Marais Erasmus declined the appeal - the sound apparently lost in the afternoon Perth breeze. Bell reacted like a man on death row, as the indication of Real-Time Snicko was enough to overturn the verdict, despite a lack of Hot Spot evidence.
Siddle celebrated this moment in a manner that suggested the finish line was imminent, but Stokes and Prior survived, averting any thoughts of the extra half-hour. For England, it was a stay of execution. For Australia, one more sleep until the Ashes.
Daniel Brettig is an assistant editor at ESPNcricinfo. He tweets here