Smith achieves his moment, England miss theirs
England 32 for 0 (Cook 17*, Root 13*) trail Australia 492 for 9 dec (Watson 176, Smith 138*, Anderson 4-95) by 460 runs
Scorecard and ball-by-ball details
It is not often that striking Jonathan Trott for six has been portrayed as a career-defining moment, but that will understandably be Australia's ambitions for Steven Smith after he completed a maiden Test hundred to quell England hopes of an unprecedented 4-0 victory in the Investec Ashes series.
This series has long fallen to England but Australia could yet cobble together a reasonably cogent argument that they are finishing the stronger and, with another five Tests in store in the Great Brown Land to come, Smith's unbeaten 138 - extended from 66 overnight - will support their contention that they can be competitive in the return.
As for this final Test of the series, England could draw comfort from the fact that Alastair Cook and Joe Root survived 17.3 overs before bad light clipped a few minutes from the second day. They will hope that their decision to field two spinners for the first time in a home Test for four years will be justified by the end of the match but, after conceding nearly 500 and with an unsettled forecast for Saturday, the odds are not in their favour.
To discover Trott trundling in as a bit-part bowler in England's attack was no bad thing for Smith with a first Test hundred in the offing. Trott had only four Test wickets to his name and Smith allowed himself an over of reconnaissance before asking Brad Haddin, his batting partner: "Do you think I could hit him over the top?" Keep a clear mind, Haddin advised and Smith did just that.
His response to the first ball of Trott's second over, a graceful loft over long-on for six, might have been the final genial blow in a practice session, a gentle mickey-take of a team-mate. Instead, as his delighted expression showed, it was further proof of a potential breakthrough.
Smith had been overshadowed by Shane Watson on the opening day. Conditions were more exacting as he resumed his innings but he reined in the most adventurous elements of his game, surviving against a ball that regularly nibbled around off the seam. His occasional full-blooded moments were well judged, which has not always been the case. When the mood takes him, he does not lack for courage.
England will sense that they wasted a good bowling opportunity. When play finally began at 2.30pm - morning drizzle having delayed the start by three-and-a-half hours - the skies remained heavy, the pitch had a darker tinge and there was more encouragement for the seam bowlers than there had been on the opening day when Australia moved blissfully to 307 for 4.
Smith's mind attuned to a more taxing task but, understandably, the same could not be said for the nightwatchman Peter Siddle, who was picked off in Anderson's third over of the day when he tried to whip the ball through midwicket and was bowled by a late outswinger.
A year ago at The Oval, England were 250 for 2 before conditions changed, South Africa hurried them out for 385 and Hashim Amla's triple century went on to ensure that England lost by an innings. With Australia five down for 320, England must have sensed their opportunity.
But England were unable to make the same impact. Anderson and Broad bowled without much luck and Chris Woakes, although he exerted reasonable control, again made little impression as a third seamer. If he had been adequate at best on the first day, he would have hoped for better in more favourable, oft-times gloomy conditions, but he carried little menace.
When Haddin on-drove him into a puddle on the boundary edge, it did not enhance England's mood. If they asked for the ball to be changed once, they must have asked a thousand times.
England also wasted a review with Haddin on 15, Matt Prior persuading Cook to turn to the DRS for an imagined leg-side glance in which the bowler, Anderson, had no interest. The ball missed the bat by a distance, underlining the feeling that England, who began the series as superior in their use of the DRS to Australia, now possess the same confusion.
By the time Smith's century arrived, followed shortly afterwards by tea, the skies were clearing and batting conditions had erased. Smith had achieved his moment; England had missed theirs. But Trott underlined that he is not quite as harmless as he appears. Four balls after Smith experienced the most fulfilling moment of his career, Haddin departed, trying to manufacture a chop behind square on the off side but deflecting the ball on to his stumps.
With 36 overs remaining at tea, and a 7.30pm finish on the horizon, Australia's main consideration was whether to have a bowl at England at the tail end of the day.
They declared with 75 minutes left after a satisfying post-tea thrash brought a further 95 runs in 13 overs. England, whose professionalism knew no shame, dawdled through only 11 overs in the first hour, three by the offspinner Graeme Swann, retreating into obsessive ball drying and continued requests to change the ball rather than actually caring much about propelling it in front of a capacity Oval crowd.
James Faulkner, a debutant allrounder who has made his name in one-day cricket, was well suited to instructions to make quick runs after tea. Three boundaries off Broad in four balls, the best of them a forearm smash over cover, gave him some fun before Woakes, in his 23rd over, took his first Test wicket when Faulkner's top-edged pull was neatly taken on the run by Trott at deep square leg.
Thirty-two overs had passed, and Australia had added 137 runs, before England introduced spin. Unsurprisingly, it was Graeme Swann, not Simon Kerrigan, whose method deserted him under Watson's onslaught on the first day. Swann needed only two balls to strike, tossing one up and defeating Mitchell Starc's lusty swing by a distance. Anderson ended a vigorous contribution from Ryan Harris with an excellent high catch off his own bowling.
As Australia hit their way towards a declaration, England eschewed the option of turning to Kerrigan. An ambitious captain would have risked another mauling to give Kerrigan his first Test wicket. A conservative captain would have protected him for another day. Cook, to no great surprise, took the path of minimal risk.
David Hopps is the UK editor of ESPNcricinfo