For Smith, it started so promisingly: the magnificence of his Brisbane century, a buoyant team, a first half of this match sailing in Australia's favour. For Root, it started under gathering clouds: a defeat, a distracted squad, and the brief boon of winning the toss turning to ashes in his hands.

But by the midpoint of the Test match, Smith's path and Root's were travelling in perfectly opposite directions. The crossroads was on Monday night when Smith declined to ask Root to bat a second time. If Root's decision to send Australia in to bat was a blunder, perhaps this was its mirror image. Even it if wasn't, England reacted as if it provided them with an opening. Perception could, as it tends to, become reality.

There is an element of mysticism to these narratives, with signs and portents to be read. Tuesday's play provided many such, and they were almost uniformly in England's favour. Good catches were taken as England capped Australia's lead at challenging, advanced, but short of genius level. James Anderson, on his fourth Ashes tour, finally took five wickets in an innings, a nice little capstone for his captain. How far into this match England had got themselves was beside the point; that they were not out of it was the thing. As they prepared to bat, their morale was on the ascent.

Meanwhile, Smith was slipping down from that peak in Brisbane, those happy days when he laughed his way through a victory conference. His cheap dismissal was part of the chaos on Monday night. Anderson, bowling right arm around the wicket, was trying a new angle that flummoxed Smith, who was only a stitch or two of Kookaburra thread from being lbw before, with the crestfallen look of an enigma that has been solved, he was struck in front by Chris Woakes.

These captaincy portents added up as England began their chase. When Josh Hazlewood struck Alastair Cook dead in front, Smith was not sure enough to risk a video referral. He was wrong. Cook did not last much longer, but the effect of the decision did.

Root began his innings looking nervous, unbalanced and even uncoordinated. He drove loosely, his eyes fell away from the level, and the middle of his bat was a long way from Yorkshire. But he battled and battled and by dint of determination worked his way into form. The chance presented itself to build a monument to equal Smith's from Brisbane.

Smith recognised the threat. The business of referrals doubled the tasks of captaincy. Both Root and Smith were in the heart of the action as combatants, but also in their roles as appellate judges. Growing anxious about his counterpart's returning confidence, the Australian captain lost a referral when he supported Pat Cummins's appeal for a catch at the wicket. Soon after, Smith, perhaps feeling he owed Hazlewood, granted the bowler a referral in another decision that was as mistaken as the first, compounding the error and heightening the sense of foreboding. As the video soup Nazi might put it: no more referrals for you.

In another portent, Root got lucky, padding up to a straightening ball from Lyon and being given out before the ball-tracker let him off the hook. Later on, he did the same again, offering both pads to Lyon. Aleem Dar was having none of the Australians' appeal. Without the option of a video referral, Smith had to watch the replay helplessly on the big screen at the Cathedral End. Just to the side, if he cared to look, a few thousand singing Englishmen were taunting him with anatomically correct referral motions.

Over by over, the wire separating these teams shortened and tightened. With Dawid Malan in support, Root sensed the potential for something very special. Cricket is a batsman's game, in the sense that the power rests in his hands. This was apparent in the contrasting demeanour of the captains. Root was urging himself on - if he could concentrate, he could win this thing - while Smith, at slip, fretted and cursed and rolled his eyes. And then a catch went down: Malan, edging Lyon, to Smith. In and out of the right hand. A difficult catch, to be sure, but the type of catch the Australians were gobbling up one short day ago.

By close of play, this drama was still in equipoise: Root still at the crease and still with a chance, Australia with the odds on their side but not the momentum. And a sleepless night ahead for the captains, something they can share in common.