Joe Root wasn't just battling to save this match. And he wasn't just battling to save his side's hopes in the Ashes. He was, perhaps, battling to save his captaincy.

Few England captains survive two Ashes series defeats to lead their side into a third. Archie MacLaren did so, but that was more than a century ago and he had been replaced in between series. Archie didn't have Twitter to deal with, either.

But it wasn't just defeat that threatened Root. It was the thought that captaincy may be getting the better of him. England had been a bit of a shambles at the end of day two and the start of day three. Root himself had put down a relatively straightforward catch at slip - Marnus Labuschagne was on 14 at the time; it may yet prove a crucial moment - they had conceded over-throws and started to snipe at one another in the field. Increasingly it was looking hard to sustain the belief that Root was the man to drive this side forward.

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More than that, Root's primary problem was the diminishing returns from his own bat. In a side as parched for runs as England, any drop of output from their best batsman cannot be accommodated. Going into this innings, Root was averaging 18.85 in Test cricket this summer having suffered consecutive ducks in his previous two innings. Overall, he averaged 52.88 when not captain and 40.41 when captain. The evidence was starting to suggest he had been worn down by the burden of the role. The whispers were growing that, for his own good as much as the team's, it might be necessary to make a change.

That would be a nightmare for England's team management. There are few obvious alternatives for the role - Ben Stokes, perhaps, or, maybe Stuart Broad for the rest of the summer - and it would spell defeat in England's rebuilding efforts of the last few years. But, tough though the decision might have been, it was increasingly looking as if it might appear necessary.

Moments after Root came to the crease, England subsided to 15 for 2 requiring 344 more for victory. It looked a hopeless task. No England side has ever made such a total to win a Test and there's not much about this side - the team that have lost 10 wickets in a single session four times in the last three years - to suggest they will be the ones to change history.

But, at last, they found some resistance. Not swashbuckling, counterattacking, blistering resistance. The more substantial kind. The kind that is prepared to wait and leave and take blows to the body. The kind that reminds us that batting isn't just about eye-catching shots, but tight defence and well-judged leaves. It's about hours of careful accumulation.

Root was beaten at times. Josh Hazlewood, in particular, bowled beautifully and might, with a slice of luck, have won the battle. But while England pushed and prodded at deliveries in the first innings, here Root defended with bat in front of his eyes, played the line and refused to be lured into jabbing at the ball as it left him. His first three boundaries were all the result of soft hands combatting well directed deliveries and guided - sometimes with more than a hint of edge about them - to third man.

As his innings progressed, there were one or two more expansive shots. When Nathan Lyon over-pitched, for example, Root leaned into a cover driven boundary that registered his half-century from 120-balls. The next delivery, Lyon dropped short and Root turned him to fine leg for four more. And when Lyon removed his slip, Root responded with a reverse-sweep for another boundary.

But he had earned the right to those strokes. He had seen off the bowlers at their freshest and the ball at its hardest. He had forced them into third and fourth spells and, for perhaps the first time this series, exposed the limitations of Australia's three-man pace attack. This is how Test batting used to look.

One of the more remarkable moments in Root's innings came when he had scored 59. It earned no applause and will probably not feature on any highlights package. But his ability to keep out one delivery from Hazlewood - a ball that jagged in and kept horribly low - was remarkable; a testament to the batsman's hand-eye coordination and the manner in which he was keeping his eye on the ball.

It was, for the most part, good old-fashioned Test batting. There was none of this nonsense about needing to be positive or putting the pressure back on the bowler by hitting them for boundaries. Instead it was about the importance of remaining compact, the importance of wearing bowlers down and the importance of selling his wicket for the highest price possible. It was, in short, the innings of a leader.

He received admirable support from Joe Denly. There have been times in this series - really quite long times, not least in this game - when Denly has looked some way short of the standard required to sustain success at this level. Even in this innings, there were times when his most productive shot was the leave; so late was he on some leaves, that the ball flashed away off the face of the withdrawing bat to the boundary.

But there should be no doubting his toughness or determination. The Australian bowlers gave him a wonderfully sustained examination against the short-ball and, while he rarely looked anything other than hugely uncomfortable, he never took a backward step and he never gave it away. Eventually, he too produced a cut, a clip and a drive or two that suggested this attack could, in time, be overcome. He earned this half-century through bravery, bruises and bloody-mindedness.

And then there's Stokes. Forget, for a moment, the fact that he reached stumps having batted 50 balls for 2. That's an admirable demonstration of restraint, for sure. But it pales into insignificance beside his effort with the ball. Had it not been for Stokes' incredible spell - his 24.2 overs, every one of them dripping with pace and hostility, were broken only by night and four balls from Jofra Archer - this Ashes campaign would have been decided already. Not for the first time, his figures - 3 for 56 and 2 not out - provide little insight into the enormity of his commitment and contribution.

Australia remain overwhelming favourites for this match and this series. With the pitch exhibiting signs of uneven bounce and a new ball due after eight overs on the fourth day, Root may consider that his work has hardly begun. It would be little less than a miracle if England pulled this off.

But Root has, at least, shown that he has the character and skill to perform under pressure. And he has shown the leadership qualities to coax performances out of his team. Maybe, just maybe, Root can lead his side through such hardships in the manner in which Allan Border did so when captaining Australia during the defeat of 1985 and 1986-87. Border, after all, then went on to lead his side to success in the next three Ashes series. There were moments, at least, on Saturday when Root suggested he had the skill and the fortitude to do something similar.