Of all the many sideshows that are sure to entertain us over the coming six weeks - and Adil Rashid and Kuldeep Yadav have recently upped the ante among them - none will demand quite the attention of the battle between the two captains. One a fresh-faced lad from Sheffield in the north of England, a place best known for steel and two football teams; the other born into a Punjabi family in Delhi, a place best known for its old and new, its Red Fort and markets, and its cricketers.
These men hold high office in a game that still accords their office power and control. In no other sport does the role of captain mean so much to the daily routine of the team, the choices it makes and the results that it achieves. Like motherhood, cricket captaincy requires a raft of attributes - Abraham's faith and Daniel's insight come to mind; so too Solomon's wisdom, the patience of Job, and the courage given to David; only the strength of Samson is on hold, mainly for T20 excursions.
Alongside these must come the discipline to practise as they preach, for they represent an ancient culture of sporting morality that, thankfully, has somehow survived the age in which it now lives. Steven Smith recently discovered the worst side of losing this discipline, from which the fallout is unpredictable, and then inevitably uncontrollable. The morality of sport can define you, and if not, it may at the very least find the momentum to swing opinions of honour and disaffection.
"Root has similar passion as Kohli - both men, by their own admission, are cricket tragics - but it is disguised by English reticence"
And yet these are perhaps the least of the challenges faced by Joe Root and Virat Kohli on Wednesday morning at Edgbaston, for they are among the best five batsmen in the world and unarguably now, the best batsmen in their teams. Therefore they must make runs. It is when these two fine and charismatic cricketers take guard - when the camera homes in on their every breath and fidget - that our forensic eye will turn to them, and to them alone.
Kohli needs Test match runs in England, having failed to find them last time he was here - a point of fact pursued by everyone and which has thus become a cliché. There is no avoiding it. To prove he is the very best of the batting zeitgeist, Kohli must confront the lands of swing and seam - his nemeses four years ago - and conquer. The warm and dry weather may make this an easier campaign than it might otherwise have been but lingering deep inside that cricketing soul of his will be the knowledge that England is a frontier. He must be sure that the desire to personally overcome it in no way gets the better of the ambitions of the team around him.
Root needs to convert his currently efficient batting into excellence. He is passing 50 more regularly than most have done before but the hundreds are eluding him. Statisticians call this the conversion rate, and of the four "moderns" - Smith, Kane Williamson, Kohli and Root - it is Root who has failed, though by only a small margin, to improve his batting average since he became captain. That poor conversion rate is the reason. Almost certainly this is because he is learning on the job, and of course, there is so damn much to learn.
Of England captains during the last half-century, he has been the one most likely to be offered the role and the one least likely to immediately adapt to its requirements. Only Michael Atherton was his junior in terms of age when he took the captaincy, and yet there was something senior about Atherton from the start - something intellectually sure that gave him a head start over his peers. In addition, there could be no confusion about Atherton's batting. The buck stopped with him; Athers was England's wall, end of story. His colleagues knew as much and doubtless resolved to not betray the strength of their captain's mind or the stamina of his performance. Unfortunately, at the time the England team was not blessed with talent commensurate with that of those it played against. Ambrose and Walsh; Wasim and Waqar; Donald and Pollock; McGrath and Warne were the chief tormentors in an era of magnificent bowling that made England, and Atherton, suffer more than they might have done at other times during this 50-year period.
Root came into the job still enthused by the objectivity of youth and all its possibilities. Remember him? The young fellow who sparkled against Australia at Lord's in 2013 with 180 carefree runs that came to an end when he was caught on the third-man boundary from a reverse ramp that would have been cheeky in the extreme if played in a rain-affected ten-over slog. England won that match by 347. How easy it must have seemed!
In the seasons that followed, both home and away, he lived and learned. Unusually for the players of the day, his back-foot play impressed more than the move forward. Smart bowlers began to work on this and turn that freewheeling strength outside off stump into a niggling weakness. As a member of the proletariat, he had time to concentrate wholly on unravelling these sudden mysteries, and in an innings of 254 against Pakistan two years ago, he appeared as near to perfection as might be expected in an era when batsmen change formats as fast as football teams change formation.
"The best of Root is to come. For now, we must all understand that his mistakes must be his own and so too the successes"
Then, at the age of 26, came the captaincy. It is worth reflecting on the diversions that will have most surprised the new boss. The five days of a Test match demand intense, and often overwhelming, focus. Through the now iconic Ashes series of 2005, Michael Vaughan confessed to no more than one or two decent nights' sleep, so active was his mind, so on edge was his nerve. The strategic challenge of six- to seven-hour spells in the field requires sharp and flexible thinking, calm responses, and a unique form of on-the-go man-management that absorbs extreme swings of mood and confidence among bowlers specifically. Rarely are two sessions alike; no day is like another. The team game and its individual performance remain the dichotomy and among each captain's greatest challenges - the contrasting attitudes of batsman and bowler; the gifts of flair and pragmatism; a collective spirit versus single-minded goals: these collide and must be monitored.
Rather than bypass them, Root has looked to be everyman. Kohli, in contrast, has ignored much of the inner mind game and gone with outward effect. His passion and exhortation, his nationalism and celebration, tell his men that he must be followed or fear the worst. Root has similar passion - both men, by their own admission, are cricket tragics - but it is disguised by English reticence. In the final one-day match between the two countries recently, Root, upon reaching his hundred, dropped his bat in the style of a pop star dropping his mic at the end of a successful show. In some quarters he was criticised for the ostentation. In this corner, he was applauded for winding back the clock to the Root of the reverse ramp.
The more we see him throw off the shackles in this way, the more he will make the captaincy his own. That innings a couple of weeks ago at Headingley, and the hundred three days before it, tell us his movements and mind are back in sync. In the one-day international weeks since the short Pakistan Test series, he has been able to clear the captaincy traffic and put his own batting first. He has loosened the tension in his shoulders, arms, wrists and hands; he is gripping the bat softly and maintains balance and flow alongside the ball rather than robotically behind it. The mind appears freer, and now so too the physical requirements of this immensely difficult and complex art.
Atherton averaged 35.2 before he became captain and 40.5 after - a man born to the responsibility. So too Graham Gooch, who was the ultimate case in point - 35.9 as a foot soldier, 58.7 as the general. Peter May is close to Gooch; Ted Dexter and Mike Gatting are impressively in the plus column. On the flip side, Ian Botham was 36.7 without the leadership collar around his neck but 13.1 when it was so tightly screwed on. Botham, of course, captained only against the mighty West Indians, who made it their business to target him. Moreover, there were many hours and overs to bowl while the ball flew off Caribbean blades to all parts. In this analysis, Sir Ian is excused and exonerated. Vaughan is interesting - 50.9 as a player, 36 as captain. Injuries, the knee specifically, began to dismantle his natural rhythm, and few men gave so much to the captaincy over two consecutive and hugely demanding series, first away to South Africa then at home to Australia in 2005.
Now, here's the one. Root is 52.8 as a player and 50.5 while captain. English fans can hardly grumble. The responsibility might weigh heavy but his early response has been to cope, albeit within a different framework of performance from previously. The next step will be to build the team in his image. This is tricky while older legs remain essential to its success - James Anderson, Stuart Broad and Alastair Cook are key figures in the coming battle - but the more runs Root makes, the more that power of his increases. The best of Root is to come. For now, we must all understand that his mistakes must be his own and so too the successes. Whatever else, the cricket team that walks out on Wednesday morning will forever be "Joe Root's team", so he might just as well impose himself on it and upon the situations in which it finds itself. When he does - and with confidence - the sparkle will return, that average will reboot itself, and the runs England need to win Test matches should bounce off him.