Preparations take place at Swalec Stadium on Tuesday.
The Swalec Stadium will be under the microscope on Wednesday for an all-important opening night.
The NatWest Series finale in Cardiff is only England's second one-day international at this venue and, to many a potentially critical eye, will decide the wisdom of scheduling the ground's Test debut for next summer's Ashes opener.
It is not controversial to recall that when the then Sophia Gardens was first confirmed as host of an England-Australia Test, approval was not universal.
Significant disenchantment was felt among the old and the new as, for example, both Manchester and the Rose Bowl lost out to Wales.
When a South African leads England out of the 'Really Welsh' Pavilion to face the old enemy next mid-summer, he and his team-mates will appreciate a home support that is not only in fine voice but singing from the same sheet.
It would not be fair to conclude that Wednesday's day-nighter will prove or disprove Cardiff's Ashes credentials.
But as dress rehearsals go, this one needs to be pretty much on cue.
There is good news already for those with a vested interest - from the mouth of the man himself, Kevin Pietersen.
The England captain's initial impressions appear highly favourable.
"I think it looks really good. It really does look like a good cricket ground," he said.
"The dressing rooms are fantastic."
Only passably better fortune weather-wise should ensure Cardiff does not next July endure the anxious moments which may characterise the next two days, with yet more rain forecast and in danger of sinking England's hopes of whitewashing South Africa.
"The key to a good cricket ground is the wicket and how well the ground drains - and we will definitely find that out for Wednesday's fixture," Pietersen predicts.
As for the support in the ground as England try to maximise home advantage against Australia, again there are no doubts from their lynchpin batsman.
"I think we'll be fine," he said.
"Everybody who plays against Australia wants to beat Australia - no matter whether you're South Africa, Pakistan, India, Wales, England, Scotland or Ireland.
"Whatever you are, you always want to beat Australia."
The clue to British unity on this one is, of course, in the very name of the body that administers cricket here.
The England and Wales Cricket Board have faith in Cardiff; their inclusive intent is obviously admirable - and Pietersen, for one, is prepared to buy into it.
"I'm sure we'll have full houses and it'll be great for the people here in Wales to have such a huge Test match and occasion coming to Cardiff," said the captain.
He has an enviably infectious enthusiasm; it must be hoped it is intact by the end of Wednesday night and, more importantly, next July.
David Clough