Mitchell Starc two wickets for Australia on day three of the final Ashes Test. (Getty Images)
London: England moved to 247 for n4 at stumps on Friday at the Oval, ending day three of the fifth Test 245 runs behind Australia.
Ian Bell and Chris Woakes were unbeaten on 29 and 14 respectively, leaving the hosts needing another 46 to avoid following on.
Joe Root was the highest scorer with 68, from 184 balls with 11 fours, while Kevin Pietersen made 50 (133 balls, four fours).
Mitchell Starc, who finished with Australia's best figures with 2 for 60, took the only wicket to fall in the evening session when he had Pietersen caught by Shane Watson.
The English have already won the five-match series, which they lead 3-0.
For an hour, while batting conditions were still excellent, Australia struggled to make any headway and squandered a referral on an lbw shout against England captain Cook from a Ryan Harris delivery that pitched outside leg stump.
Paceman Starc was particularly wayward, bowling one delivery so wide that it eluded first slip on its way to the boundary.
However, the breakthrough came when Cook was caught behind to the third ball after the drinks break, pushing at a delivery from Harris that he could easily have left outside his off stump.
That ended England's best opening stand of the series at 68 but the hosts were otherwise untroubled and Root reached his fifty when he pulled Peter Siddle to square leg for a single in the penultimate over of the session.
Under more overcast skies, Australia stifled England after lunch although Root was unbothered until the 54th over when he tried to sweep Nathan Lyon and was caught by Watson at backward square leg off a top edge.
Trott faced 78 balls before hitting a boundary and another 11 overs went by before the next four, which came when Steven Smith's full toss was driven to the rope by Pietersen.
The pitch showed some signs of turn but Australia's decision to take the new ball as soon as it became available was instantly vindicated.
Starc ripped the ball into Trott's pads at the start of the 80th over and, after a seemingly interminable delay, umpire Aleem Dar raised his finger - a decision Trott unsuccessfully referred.
The scoring rate slowed even further after tea, with the first 10 overs producing just 20 runs and by this stage the crowd was cheering singles.
Australia used up their final referral when Siddle rapped Pietersen's pads with a ball that him outside the line of off stump.
Pietersen reached his 50 with an ugly pull shot off James Faulkner that squirted past off stump for four, but he was out without adding to his score in the 101st over when he was caught at first slip.
Dar reviewed the catch as Pietersen initially stood his ground, but replays confirmed the ball had carried.
Woakes arrival for his first test innings briefly added some impetus as cover drove his first ball for four and as the light faded the debutant looked assured as he batted out the session with Bell.