JOE Root's maiden series as England Test captain is an intriguing and exacting prospect.

South Africa are tourists who have effectively ended the tenures of three successive previous England captains – and have lost here just once, back in 1998, in five visits since their readmission to Test cricket.

The natural end was nigh for the eras of Nasser Hussain, Michael Vaughan and Andrew Strauss.

But defeat, or in Hussain's case the small matter of a triple-century opening stand between his opposite number Graeme Smith and Herschelle Gibbs in the first Test, hastened the process.

That then is the recent history. Step forward Root's new England for the present and future.

The Yorkshireman will begin his task with much potential in the ranks, and opponents arguably not of the greatest South African vintage, but a raft of variables running through both teams too.

For starters, Root has had a curiously long time to plot and ponder how he will go about things when the action starts at Lord's on Thursday.

It has been almost five months since he was confirmed as Alastair Cook's successor and very nearly another two before that when England last played Test cricket – ending their arduous tour of India with a fourth consecutive defeat, by an innings and 75 runs in Chennai.

It seemed clear there and then that Cook was done with the job and Root would almost certainly be his replacement.

No-one was saying so, though, and it took until February before Cook officially called time. A week later, Root was answering the first of countless questions about his approach to one of the most taxing jobs in sport.

In the intervening months of Test inactivity, the sands have been in constant shift as uncertainty prevails over the likely personnel with which Root will seek to beat South Africa.

England's bowling attack still centres on record-breaking pair James Anderson and Stuart Broad, for example – but at what point do Root and coach Trevor Bayliss begin to plan for the end of that outstanding partnership.

Anderson, who will be 35 during the third Test, has a seventh Ashes series in his sights next winter.

Injuries have started to interrupt his plans of late, though – and as well as the groin problem which stopped him in his delivery stride at Old Trafford in mid-May for Lancashire, Broad has since been troubled by a recurrence of pain in his left heel.

His fellow Nottinghamshire seamer Jake Ball has encountered more knee trouble and worst of all, the admirable Chris Woakes is set to miss the first two Tests with his side strain.

It all leaves Root and England's selectors to factor in injury, age and form as they try to assemble the right combination of young and old in the immediate and longer term to manage an able attack in flux.

Further up the list, Root can be certain of one thing – that Cook, prolific back at Essex, will open the batting.

The name of his partner for the majority of the summer is less clear after Haseeb Hameed followed his breakthrough, injury-curtailed winter in India with travails for Lancashire.

If England have questions to answer, though, South Africa's are more evident still.

When they take the field at Lord's, they will be sent out by a coach probably starting his final series and may, like England, be led out by a novice captain.

Russell Domingo has been hesitant over his decision whether to apply again for his own position.

Faf du Plessis, meanwhile, is not even in England at present – waiting for the birth of his first child back home with a due date of July 6, day one of the four-match series.

His fellow batsman Dean Elgar will deputise as captain if necessary, in charge of a team with two more notable absentees.

For much of the past decade, South Africa have relied heavily on AB de Villiers for runs and Dale Steyn for wickets.

This Test summer, they will have neither as their premier batsman ponders his Test future at the age of 33 – having long made himself unavailable for this series – and their number one strike bowler continues his recovery from a shoulder injury.

They are undoubtedly depleted then – but even in transition, South Africa will be significant opponents.

The batting may look a little fragile this time round and their vexed white-ball summer of twin defeats to England and early elimination from the Champions Trophy under De Villiers' captaincy cannot have helped morale.

The tourists' pace attack remains formidable, however. Kagiso Rabada is one of world cricket's emerging forces, while the bounce and angle supplied by Morne Morkel and Vernon Philander's suitability to English conditions will present a major test for whoever is deployed in the home batting line-up.

Match-winners Ben Stokes and Jonny Bairstow should help to give England the edge over five hectic weeks but for Root especially, the learning curve is about to take a steep turn.