Steven Smith transcends the contest as Pat Cummins puts one hand on the Ashes

It's been suspected all summer long, but at last we have definitive proof. Steven Smith is playing a different game to the rest of the combatants in this Ashes series. How else do you explain the events of the fourth day at Old Trafford, a day on which his ninth consecutive Ashes half-century carried Australia to the brink of what will surely be their first successful defence of the Ashes in England since 2001.

Hot on the heels of his 211 in the first innings, and into the teeth of a frenzied bowling onslaught from Stuart Broad and a reinvigorated Jofra Archer, Smith made light of Australia's pre-tea scoreline of 44 for 4 to josh and flinch, and poke and swat his way to a bafflingly indomitable 82 from 92 balls.

It was Smith's lowest score of the series maybe, but incredibly, for the fourth time in five dismissals this summer, his departure was more or less self-inflicted. With a lead of 345 already in the bag and Australia straining for a late-evening declaration having bowled England out for 301 in their first innings, Smith's inside-out carve picked out Ben Stokes at deep extra cover to complete a match aggregate of 293 runs - a tally which accounted for more than three-quarters of England's eventual target of 383.

Steadfast in adversity then cocksure once on top, Smith had to ride his luck against Broad in particular, who was magnificent, but backed his peerless judgement on an afternoon when the rest of Australia's top five managed a top score of 12 between them. That included the hapless David Warner, to whom Broad delivered the first pair of his Test career, while bagging him for the sixth time this series, and for the seventh single-figure score out of eight in a grim campaign.

And then, as if to confirm just how other-worldly Smith's efforts really had been, in steamed Pat Cummins with the shadows looming at the start of a nervy mini-session for England's top order. Four balls into his evening's work, he had torn out the spine of England's intended rearguard, inducing a third-ball leading edge to have Rory Burns caught in the covers for a duck, before serving up an absolute snorter that pinged the top of Joe Root's off stump for a golden duck - the perfect line, the perfect pace, and - unlike the one that zagged into Root's pads in the first innings - the perfect jag off the seam to beat the outside edge of his crestfallen bat.

The rocks of England's first-innings reply had been shattered, and though Jason Roy in his current form would have been Cummins' dream pick for a hat-trick target, he endured to the close alongside Joe Denly to carry what remains of England's fight into the fifth day. For let's be realistic - for all that England hunted down 359 to complete the miracle of Headingley, this Old Trafford pitch is a different beast entirely, offering stump-threatening skid and late movement to those who pitch it up, not least the lesser-spotted Mitchell Starc, whose three wickets in the morning session had been a harbinger of the dramas to come.

Starc had been Australia's weak link at the start of England's innings, bowling just 11 expensive overs on the third day as Cummins and Josh Hazlewood showed the way for their side with their devotion to sharp pace on a good length. But with England resuming 98 runs shy of saving the follow-on, and charged with extending their innings as deep into the day as possible, it was Starc's swing that tore the stuffing out of their morning's efforts. Jonny Bairstow was bowled on the drive by a hooping inswinger (for the 32nd time in his career) before that man Stokes succumbed for the first time since the Headingley first innings, expertly extracted by a curler on off stump that he couldn't help but nudge to slip.

For the remainder of England's innings, it was hard to know whether to stick or twist - to reduce the deficit quickly before the wickets ran out, or to stick to the original gameplan of eating as much time out of the game as possible. In the event, it turned into a curious tribute to that Headingley run-chase, as the tail rallied around Jos Buttler to tick off the runs required for a small psychological win - the avoidance of a follow-on that Australia almost certainly would not have enforced anyway. They duly managed it, with Jack Leach once again resolute at No.11, but when Buttler missed a slog to be bowled for 41, the remaining deficit of 196 was still pretty daunting.

When England emerged for Australia's second innings, however, with Stokes - tellingly - giving the team-talk as they huddled before the first ball, it was clear that the spirit of Headingley was still infusing their self-belief. Six balls later, there could be no doubt at all. In spite of his flatlining form, Warner remains one of the most deadly second-innings batsmen in the game, especially when presented with the chance to build on a lead. Half an hour of his devil-may-care thumping could have cooked England's goose by the tea-break. Instead he was thumped on the knee-roll by a pumped-up Broad, and sent on his way for his third duck in a row, a massively motivating scalp for the team and a partisan crowd.

Six overs later, Broad repeated the dose to extract Marcus Harris in identical fashion - round the wicket, swinging in, pinned in front of middle and leg, and when Broad scuttled his second ball to Smith, who jammed his bat down late to dig it off his stumps, battle had been well and truly joined. Not least by Archer, who might well have been piqued by the reaction to his first-innings display, but was undoubtedly riled by the sledging he had received during a brief innings in which he had almost run himself out first ball.

Suddenly his pace leapt back up by that missing 5mph, and the crowd revved up in response, as Marnus Labuschagne became the third lbw of the innings - again round the wicket, again clipping leg, and cheekily waved goodbye by Broad as he turned to offer some chat to the England huddle after unsuccessfully reviewing. Travis Head then had his middle stump dynamited on the same angle, as he too paid the price for engaging Archer in verbals in the course of an over that peaked at 93mph.

But throughout it all, Smith batted with the abandon of a man who had already been batting for 319 balls on this surface. At times, he seemed so carefree he seemed liable to pop his own bubble, but such is Smith's talent, that even when he seems not to be fully focused, he retains the wherewithal to avoid errors against the genuinely threatening deliveries, and to keep the score ticking ever upwards.

Even so, Broad continued to hound him like few bowlers have managed since that Archer duel at Lord's, and on 28, he came excruciatingly close to playing on as he dug out a yorker - the first ball of a new spell - and watched it trundle millimetres past his leg stump. And then, on 48, came the moment of near-genius that all but dislodged a genius. As Smith stooped to reverse-sweep the leaky spin of Leach, Stokes at slip saw him inverting his stance and sprinted to gully, where he dived to his right and all but clung onto a stunning catch in both hands. But the ball wriggled out and the moment was lost. So too, the last chance for England to dictate any remaining terms in the innings.

By the close, the die was cast. England limped to 18 for 2 at stumps - an outstanding deficit of 365 that Stokes, Bairstow, Roy and Buttler would find a challenging ask in white-ball cricket, let alone red. Consecutive miracles is asking too much of any Ashes campaign. Especially when it's the opposition's star player who is batting like a God.