Theunis de Bruyn, who played his only Test in New Zealand in March, is likely to replace Du Plessis in an inexperienced line up which also features Heino Kuhn on debut at the top of the order.
It was an uncomfortable moment on an otherwise excellent first day for England's new Test captain.
If Elgar's promotion was unexpected, Root's is anything but; he earned the moniker FEC (or Future England Captain) in the youth teams at Sheffield Collegiate, helped as much by comparisons to Michael Vaughan as a classy, flawless technique. So often on this first day we've seen him just angle the ball gently away for four.
Ballance, who is averaging more than 100 in the County Championship for Yorkshire, reached 20 before he was dismissed.
The 27-year-old played seven Tests and 27 one-day internationals for his country before retiring from the sport in April 2016 due to a serious heart condition. I'm a little bit bunged up but I'm making the most of it.
The circumstances of England's second early departure were regrettable.
As the shadows lengthened the runs came quicker still, Moeen unfurling some sumptuous cover drives and Root using his feet to attack the spinners to fine effect. When you get a life early you feel like it is your day, and you've got to try and make the most of it.
Captain Joe Root top-scored with 190 in England's total of 458 in the first innings of the first Test against South Africa at Lord's
And it meant England closed the first session of the First Test against South Africa on 82-4, with Root not out on 33, alongside Ben Stokes, who was unbeaten on four. But with Ballance back on his stumps, technology showed the ball would have hit middle and leg stumps. Meanwhile, among the highest scores on debut as a captain, Root is now in the fourth spot.
Kohli and Smith had posted hundreds in their first innings leading their respective teams in Test cricket, both during India's 2014-15 tour of Australia.
Meanwhile Domingo, who has confirmed he will re-apply for his job as required by South Africa officials, had to return home briefly after his mother was involved in a traffic accident.
In spite of these chances created Rabada bowled too many deliveries wide of the stumps as he struggled to come to terms with the Lord's slope from the Nursery Ground end but, apart from three no balls from Philander and Morkel, in the first three overs it was largely a well-disciplined bowling performance from the three seamers supported by three tight overs from Maharaj immediately before lunch.
Where will the England vs South Africa 1st Test match be played? A top-edge on five sailed over an ill-stationed long leg, before JP Duminy failed to cling on to a flashing edge at gully on 16. Umpire S Ravi took his time before raising the finger, with England eventually opting against a review.
Then Ballance reviewed his lbw when he looked absolutely plumb.
England careened past 400 as Broad flashed and dashed with all the control of a man trying to bat on a skateboard.
"People look up to him, naturally, by the way he goes about his cricket".