The tone was set just before lunch when, faced with an uncomfortable nine overs and chasing a middling target of 217, Smith and his opening partner Boeta Dippenaar set off like a rocket. Dippenaar was the aggressor, crunching four boundaries to settle South Africa's nerves who went to lunch on 49 without loss; before this game, only three times had South Africa successfully chased down more than 200 runs in the fourth innings. They were let off by New Zealand's bowlers, though, who wasted the new ball and handed the momentum - at a key stage of the match - to the batsmen.
Smith and Dippenaar continued their confident start after lunch, too. And much as South Africa's bowlers had suffered with their lengths in the morning, so did New Zealand in the afternoon session. Too often, Martin bowled short allowing the batsmen to rock back and power him through the covers. When he did pitch it up, batting was trickier, as Dippenaar found out when a fuller delivery caught his outside edge and flew to Brendon McCullum to end a 69-run opening partnership.
Undaunted, Smith continued to hit boundaries to take the initiative away from New Zealand, powering Scott Styris for a vicious four over midwicket before clobbering James Franklin for two further fours. His fifty - his second of the match - came up with a crunching back-foot drive which rather signalled that the end was nigh for New Zealand.
With South Africa settled on 114 for 1, Stephen Fleming turned to Daniel Vettori for a breakthrough who was immediately sent packing; coming down the pitch, Smith lofted him over his head for four, narrowly avoiding long-on, before smashing him for six off the next delivery. Vettori didn't bowl again in the innings.
Smith got carried away, though. After glancing Franklin fine for another four, he got cramped for room attempting the same shot. Hashim Amla, too, paid the price for over-eagerness - anyone would think they had a train to catch. After playing reasonably well for his 28, with the game seemingly in the bag, a lazy flick through midwicket off Kyle Mills saw the ball cannon into his stumps. It was a poor, careless dismissal from a batsman who too frequently flits between the excellent and the dreadful.
Mills, bowling with surprising pace and lift, accounted for Jacques Kallis too. And when Franklin bowled AB de Villiers for 8, South Africa's bullish counterattacking started to look a little foolish, especially considering the amount of time still left in the game. However Ashwell Prince - who is fast becoming South Africa's second middle-order rock - remained solid, calmly picking up singles to take South Africa home safely with an unbeaten 43.
Given the nervy run-chase - this is only the fourth time South Africa have successfully chased over 200 runs in the fourth innings - New Zealand were perhaps only fifty runs short of setting South Africa a truly testing total. With Jacob Oram and Daniel Vettori both playing sensibly, seemingly unflustered in the morning session, a target in excess of 250 was within their grasp. Oram misjudged the length from Dale Steyn, though, ballooning a difficult but well-held chance to de Villiers at mid-off to end their 49-run stand.
Vettori and Franklin were similarly untroubled for much of the morning; as South Africa's shoulders dropped, so did the bowler's lengths. Time and again Vettori was allowed to rock back and hammer fours through the off-side, or glance a fortunate edge down to his favoured third-man region. Curiously, Shaun Pollock was held back from the attack until the 15th over and it was he who broke through Franklin's thoroughly impressive defence. Andrew Hall then mopped up the rest as New Zealand stumbled, failing to add to their score having sat comfortably on 283 for 7.
That South Africa were so keen on finishing the job in double-quick time said much about a side that has, on occasions this season, struggled to take the initiative and close the door on their opponents. Their aggression paid dividends, however, and Smith - who received the Man-of-the-Match award for his two fifties - has ended the season on a winning note and, at last, with runs to his name.
Boeta Dippenaar c McCullum b Martin 37 (69 for 1)
Regulation edge to the keeper
Graeme Smith b McCullum b Franklin 68 (130 for 2)
Cut, cramped for room, thin edge to wicketkeeper
Hashim Amla b Mills 28 (156 for 3)
Left him slightly but a dreadful heave across the line, missed it by a mile
Jacques Kallis c How b Mills 13 (167 for 4)
Squared up, fended to gully
AB de Villiers b Franklin 5 (180 for 5)
Inside edge onto top of off-stump
Mark Boucher b Franklin 6 (202 for 6)
Dragged a wide one onto his stumps
Jacob Oram c Dippenaar b Steyn 27 (239 for 7)
Misjudged length, looped to mid-off who dived forward to take an excellent catch
James Franklin b Pollock 19 (283 for 8)
Shouldered arms to a nip-backer
Daniel Vettori c de Villiers b Hall 60 (283 for 9)
Squared up, thick edge to gully
Chris Martin c Amla b Hall 0 (283 all out)
Spooned to square leg
Will Luke is editorial assistant of Cricinfo