It was brutal, and for much of the afternoon session it was relentless. But most importantly for South Africa, their prodigious use of the bouncer wore New Zealand down, and so in the end it was effective.
Vernon Philander cleaned up yet again, taking six wickets to achieve the record everyone had on their mind: 50 dismissals in seven Test matches. It had been 116 years since a bowler had managed that, and it may take another 116 before it happens again.
By now we all know what Philander's success is based on, because it has been analysed to within an inch of its life after every Test that he has played. He's extremely accurate, he can move the ball both ways and he's constantly "asking questions of the batsman."
But on day four he owed as much to the manner in which Dale Steyn, Morne Morkel and Marchant de Lange battered New Zealand into submission on a pitch with very little lateral movement. As Philander put it: "This attack gives me the freedom to do what I need to do."
There's something thrilling about watching a good attack rough batsmen up, and it comes from that part of the human psyche which is both attracted and appalled by the idea of gore. Short-pitched bowling takes the game of cricket into another dimension, one where the importance of physical survival outstrips that of wickets and runs.
We want to see blood, to wince as bones are broken, yet another side of us is disgusted by those instincts. Whether you're on the receiving end of a barrage, or simply watching from the sidelines, fear is the prevailing emotion.
"A few of their guys don't like the short ball," Philander explained afterwards. "It's been part of our plan to exploit the short-pitched bowling and rough them up. It's not part of my plan, but we have the firepower in Morne and Dale and we use it to best effect."
South Africa had done so from Sunday evening, when New Zealand began their innings, but ramped it up a notch on Monday afternoon as the ball grew old and the pitch became flat. Although they weren't rattling along, New Zealand were putting together little partnerships that were frustrating the South Africans. Had they reached the second new ball with just two or three wickets down and no broken bones then the draw would have been the heavy favourite.
Three deliveries ensured that they did not. Brendon McCullum had put on a breezy 50-run stand with Martin Guptill in the morning, but made the same mistake he did in Hamilton - taking on one too many short balls from Steyn. A top edge through to the wicketkeeper sent New Zealand's best batsman of the series on his way.
Dean Brownlie fell victim to Philander when he hooked to fine leg, but the most brutal of the three short-ball dismissals came prior to that. Brownlie and McCullum lost their wickets, but Ross Taylor was put out of action for two innings by Morkel, whose remorseless bouncer was directed with little but injury in mind. With nowhere to hide, Taylor was hit just above the wrist and his Test was over, the ulna bone on his left forearm fractured.
It wasn't the first knock taken by a New Zealander - Daniel Flynn admitted that he had a couple of good bruises on the ribs and many of his teammates will have similar stories - but it was the headline-maker that brought the efficiency of South Africa's physical barrage into focus.
It was something they used effectively in sweeping the one-day series three-nil. If they go on to win this Test match, it could well have been the defining tactic.
Tristan Holme in Wellington