Root proves he can bat in all moods
It must be disconcerting to have a Test match taken away from you by Joe Root. Like being mugged by a toddler, the face seems too fresh and boyish to resist the brutality of fast bowling or cope with the pressure and intensity of a full house at Lord's.
But Root can cope. No career comes with guarantees and Root will, no doubt, experience some lows amid the highs. But this century, the youngest by an English batsman in an Ashes Test at Lord's, cemented Root's position at the top of the order for the next decade or more. When Alastair Cook and Andy Flower and Stuart Broad and Kevin Pietersen are all pursuing careers as coaches or television pundits, Root will calmly, smoothly, tidily be winnings games for his country.
Root's maturity belies his choirboy face. He is only 22 and this is only his seventh first-class match of the summer but when he reached 70 he became the first man to reach 1,000 first-class runs in the 2013 English domestic season. By the close, he was within an ace of taking his season's average above 100. As befits his status as a saviour of English cricket, it was surely fitting that, when he was attacked by David Warner in that Birmingham bar, he simply turned the other cheek.
We knew Root could bat, of course. Since the moment he took guard on Test debut in Nagpur he has displayed the technique and the temperament to prosper at this level. He has the calm demeanour of a bomb disposal expert and a defence that can keep out the rain.
He can play some shots, too. His wagon wheel for this innings shows a man with a wide array of scoring opportunities; a man who is excellent off front and back foot, plays delightfully straight, admirably late and can change gear when required. Have England produced a more technically adept player in the last 20 years? Or might such praise be premature?
After all, Root should have been dismissed on 8 when he edged between Brad Haddin, who is quietly enduring a modest series with the gloves, and Michael Clarke. Had the catch been taken, Root would have failed to pass 50 in six innings as an England opening batsman (four in this series and two in the warm-up match against Essex) and speculation about his position would have grown.
But the England management would have taken no notice. They like what they see with Root and, unlike the talents of the past such as Graeme Hick or Mark Ramprakash, are determined that his ability should not be wasted. They were committed to him in the long-term come what may, though this innings will make the journey a little more comfortable.
This innings provided Root with an opportunity to showcase his range of skills. At first, both on the second evening and the third morning, he was challenged to survive. He was obliged to display the compact defensive technique, the judgement over which balls to leave and the concentration that will become legendary.
Later, as he settled and it became clear that this seam attack, for all its honesty and persistence, lacked the skills to threaten him, he began to pick off the poor ball with more confidence. He stretched forward to ease slightly over-pitched deliveries through cover and he rocked back to drive anything short the same way. Whereas he used to play in the air through midwicket, now his improved balance allows him to drive down the ground and turn the ball off his legs with less danger. A couple of the straight drives had Lord's purring with pleasure.
Then, as the bowlers tired, he had an opportunity to attack: long-hops were pulled for sixes, sweeps were improvised and, while his first fifty occupied 122 balls and his second 125, his third took only 64. If there is a fourth, and there may well be, it will be quicker still.
Root's greatest strength may be his ability to tailor his game to the match situation. Whether he has been required to block for a draw, as was the case in Nagpur, or accelerate towards a declaration, as at Headingley, he has shown the awareness, the confidence, the range and the selflessness to do it.
There was nothing soft about this innings. The Australian seamers, fine bowlers let down by their batting colleagues, probed around his off stump at good pace and, by tea, the pitch appeared to be deteriorating surprisingly quickly and offering turn and uneven bounce; a sight that must have provoked something close to despair in the Australian dressing room.
Even when the bowlers sledged him, Root looked up and laughed. And if there is one thing that irritates a fast bowler more than batting through a day against them, it is laughing in their face. He rarely pulled and Australia might have tested him with the second new ball, but the sense was of a mature batsman playing within his limitations who, by that stage, would have coped just fine with whatever Australia could throw at him.
Root later joked that his brother Billy, 12th man in this game, was "probably nastier than Shane Watson" during his regular trips to the middle. "He abused me all day while bringing drinks out," Root senior said. "He was just being his cheeky self, winding me up. He was telling me how slowly I was batting and how he would have smacked it to all parts."
There was no need to try to "smack it to all parts". This was only the third day, after all. There are different ways to be ruthless; this is England's way. Those suggesting England should have taken a more urgent approach on day three are missing the bigger picture. This innings was not just about extending the lead beyond the horizon and it was not just about giving the pitch another day to wear and deteriorate. Nor was it just about providing more time for England's bowlers to rest.
It was also about breaking the spirit of the Australian team. It was about forcing their seamers into fourth and fifth spells; about forcing them into another round of warm-ups and warm-downs; forcing them to pull their boots over tired, swollen feet and force aching joints into action again and again. It was about grinding them into the dust of this Lord's pitch and ruining them for encounters to come. After all, there are another three Tests in this series and five more to come down under. Mental disintegration they used to call it.
To Australia's immense credit, they kept at it admirably. There were beaten, certainly, but not broken. Not until Root and Bell were well into their partnership did runs start to flow. Not until Michael Clarke decided to protect his seamers for battles to come was the paucity of the spin attack exposed.
But batting in a hopeless situation will test that Australian resolve. There has been little about their batting in the first three innings of this series that suggests they are about to resist for five-and-a-half sessions. And they will know that, if they go two-nil down, it will take a miracle to salvage anything from this series.
George Dobell is a senior correspondent at ESPNcricinfo