Root on standby to open England's innings

Roy was able to bat in the nets on the eve of the series opener, unlike 24 hours earlier, but took only limited part in fitness drills on the Mangaung Oval outfield and none at all in England’s football kickabout.

The opener is nursing a bad back, having suffered an unaccustomed spasm, and England have already had to work out contingencies in case he does not recover in time.

Captain Eoin Morgan ran through them at his preview press conference, and appeared to favour the possibility of Yorkshire’s Joe Root opening the innings for the first time in this format – with England’s utility batsman James Taylor then getting a game after all, at No 3.

It is harsh on Taylor that there is no obvious position for him in England’s current first-choice XI, even though his century in Saturday’s warm-up win over South Africa A in Kimberley followed a sequence of more than 300 runs in his last seven ODI innings – at an average of 60.6.

Roy’s readiness, it seems, will determine whether Taylor scrambles into a team welcoming back both Root and Ben Stokes – the men missing to accommodate the diminutive batsman in each of England’s last two series.

On the evidence of half-an-hour of batting and short-lived exercise beforehand, during which Roy more than once clutched his lower back, it appears too close to call.

Morgan certainly was not pre-empting the decision when he said: “He had a back spasm yesterday... if a fitness test is required in the morning he will go through that.

“He has not had it before, so it was a bit unexpected.

“It is one of those things that might cure itself after another night’s sleep, a rub and a stretch.”

Plan B for Alex Hales’s opening partner appears to centre on either Root or all-rounder Moeen Ali – who did the job during last year’s failed World Cup campaign.

“We have a number of options,” said Morgan. “It is a luxury really.

“We have had Moeen Ali bat at top of the order and we have Joe Root who could slip up the order.

“We have James Taylor who could come in and bat at three, so certainly there is a number of options we have.”

As for Taylor’s run of form against the white ball, he added: “If he does play he will be in great nick; if he doesn’t it just means he is next in.

“It does create a bit of a problem when guys continue to score.

“It continues to expand our group of players that we are trying to develop in the lead-up to world tournaments.

“We are not trying to have 11, 12 or 13 players; we are trying to get 17 players together, so they are all pushing for places at any given time.”

Morgan is encouraged by the competition for places.

“More often than not, it happens in successful sides. It makes me proud of the squad when guys continue to score runs even though they may not be in the hunt of gaining a place in the side.

“We don’t know our best XI yet, and I think that is really exciting. We are still striving for the right combination.”

Stokes’s return as a pivotal all-rounder is an important addition to the team which won nonetheless against Pakistan in the United Arab Emirates before Christmas.

Morgan said: “One thing that does help is Ben Stokes coming back in. It balances our side really well.

“We are very flexible in our batting line-up, and Ben Stokes coming back into the squad gives us another aggressive attacking option – so it is looking good.

“It is extremely exciting.”

There is a fluidity to England’s batting order too, as demonstrated when the brilliant Jos Buttler was shunted up to No 4 in their last match in Dubai – where he proceeded to break his own record for his country’s fastest century of all time.

Morgan can scarcely deliver a much bigger compliment than mentioning the wicketkeeper in the same breath as South Africa’s AB de Villiers – the world’s No 1 ODI batsman.

“Training with him every day is, I assume, like training with AB de Villiers,” he said. “He is always looking to learn and improve on his shots.

“One thing for him, I know he strives to improve on it, is his consistency.

“On his best day, he can win a game for us – but on his half-good day, he still wants to win for us.

“The more he plays the more he can improve on that.”