For Williamson, whose dismissal for 109 left his side with a 528-run lead at stumps, a greater green-and-gold challenge cannot come soon enough, his supreme form exemplified by taking 125 balls to reach three figures.
For Tom Latham and Devon Conway, conversely, the third afternoon against a second-string Proteas represented an opportunity lost, the clock ticking before a two-test series against Australia.
That pair’s recent struggles could have played a part in skipper Tim Southee applying for an extension on Tuesday when the match had been threatening an abrupt end at Bay Oval.
The Proteas’ attempt to approach their hosts’ first-innings score of 511 had progressed about as well as expected for a side with six debutants, dismissed for 162 near the halfway point.
But sitting pretty with a 349-run advantage seemingly well beyond the tourists’ reach, Southee opted against enforcing the follow-on, watching Latham and Conway rejoin him in the pavilion before the close.
The forecast clear, New Zealand are in no danger of running out of time to take the 10 wickets they will eventually need, and there are benefits to batting again.
Resting his bowlers’ legs — and putting more miles on the opponents’ — often features prominently when a captain allows a vanquished batting unit to regroup.
That was less applicable in this instance, though, given South Africa’s 73-over innings was bifurcated by a night in bed. The three seamers’ had combined for only 42 overs, with the latter stages dominated by spin pair Mitchell Santner (3-34) and Rachin Ravindra (2-16).
Tim Southee and Rachin Ravindra celebrate the dismissal of Keegan Petersen. Photo / Photosport
Instead, one motivation for again strapping on the pads might have been the two players whose rushed exit from the field provided a strong clue to Southee’s intentions.
Latham isn’t too far removed from a couple of half-centuries last summer at the Basin Reserve and Hagley Oval — the venues for next month’s showdown with Australia. But following an lbw dismissal for 3, he is averaging 14.9 from his last eight test innings, requiring runs before the arrival of the world No 1.
Conway, similarly, hit two fifties a year ago at the Basin. Yet his battle for form was evident in the way he scratched to 29 from 68 while Williamson was making batting appear a breeze.
That was the opener’s best score from his last 10 innings in all formats, having failed to raise his bat since beginning the ODI World Cup in October with an unbeaten 152.
It could seem premature to look so soon ahead to that series, but South Africa’s shadow team have brought little intrigue. After the Proteas resumed on 80-4 today, Matt Henry struck twice in three balls from the sixth over, quashing any rearguard before it began.
That was when Santner applied the clamps, bowling an outstandingly methodical eight-over spell in which he claimed a wicket while conceding five runs, in turn probing the stumps and spinning the ball away.
When Ravindra shut down the other end, removing 12-test veteran Keegan Petersen for 45, the end was nigh.
Williamson subsequently added the type of quick runs Southee must have envisaged, starting vastly more aggressively than on the opening day. He sailed to his 34th half-century from 75 balls before being dropped for the second time by Edward Moore, this miscue much worse than the first.
Unfortunately for Conway, Moore was less generous from the opener’s slog-sweep attempt, continuing a worrying run ahead of his maiden encounter with the formidable Australian test team.
