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The St George's Park pitch is expected to be on the lower, slower side - certainly more so than the lively Newlands pitch, scene of last week's innings and 27-run loss in Cape Town - so New Zealand must play a spinner.
But team management may have given a hard think to playing four seamers, using Chris Martin and Neil Wagner to play alongside Trent Boult and Doug Bracewell.
That would come about if they were uneasy about both Jeetan Patel and uncapped Bruce Martin.
Patel was picked apart by South Africa in the first test. Left-arm spinner Martin, a 32-year-old touring novice, would be more appealing against the largely right-hand South African batting line-up.
If coach Mike Hesson and captain Brendon McCullum accept a spinner must play, Martin has a good case, providing they trust him in his first test to do the job more effectively than Patel managed last week.
The other issue is Chris Martin or Wagner. The 38-year-old Martin got better as South Africa's innings in the first test wore on, and has been a reliable source of wickets against South Africa down the years.
But left-armer Wagner has been lively in the nets this week.
There is a snag. Boult, James Franklin and Wagner - plus possibly Bruce Martin - make at least one too many left armers in the attack.
The team management has been tight-lipped this week. Where often it is possible to pick up a nod, wink or whisper that a particular hand is about to be played, this group hasnot let anything slip.
The week has been given over to hard work in the nets and trying to imbue themselves with positive thoughts after the second-innings batting of century maker Dean Brownlie and wicketkeeper BJ Watling.
Certainly the pitch is likely to help New Zealand's batsmen in their confrontation with South Africa's speedsters. So, too, is the absence of cracking South African seamer Vernon Philander.
The flip side is how New Zealand is going to take 20 wickets to square the series.
That may be a laughable notion after Cape Town, but if the players do not go out trying to pursue that objective, there is little point even leaving the pavilion tonight.
For South Africa, the situation is far simpler. Big Rory Kleinveldt will replace Philander and that will be that. Life is good for the Proteas test team right now. But their record in Port Elizabeth, the oldest of the country's test venues, is distinctly ordinary.
''I thought they batted really well in the second innings,'' Rory Kleinveldt, Philander's replacement, said of New Zealand yesterday.
''Their confidence is quite high coming off their second innings so we have got to be on the money come Friday.''
Meanwhile, all-rounder Grant Elliott has been called into the Black Caps squad for the one-day international series against South Africa as a replacement for the injured Corey Anderson.
Anderson sustained a fracture to his left thumb when he was struck on the hand while bowling. He will be in a cast for the next two weeks and his return to cricket is unclear.
Johannesburg-born Elliott last played for New Zealand in 2010 against India and has made 37 ODI appearances for the Black Caps.
SA v NZ
Port Elizabeth, 9pm start
South Africa (likely): Graeme Smith (c), Alviro Petersen, Hashim Amla, Jacques Kallis, AB de Villiers, Faf du Plessis, Dean Elgar, Robin Peterson, Dale Steyn, Morne Morkel, Rory Kleinveldt.
New Zealand (from): Brendon McCullum (c), Martin Guptill, Kane Williamson, Dean Brownlie, Daniel Flynn, BJ Watling, James Franklin, Colin Munro, Doug Bracewell, Jeetan Patel, Trent Boult, Neil Wagner, Bruce Martin, Mitchell McClenaghan, Chris Martin.