Only 37 overs were bowled Saturday between a rain-delayed start and the intervention of poor light at 5:24 p.m. local time, more than an hour before the scheduled close of play. In that short period, Petersen advanced his score from 44 not out overnight to within four runs of a century which has breathed new life into his test career.
J.P. Duminy was 76 not out at the close of play after adding 140 with Petersen in an unbroken stand for South Africa's third wicket.
The 31-year-old Petersen had scores of 11, 25, 29 and 1 in his previous innings in this three-match test series and his position at the top of the South African order was under serious threat.
Petersen has batted throughout the South African innings, enduring rain-delayed starts and early finishes, stoppages caused by rain, cold conditions and finally a buffeting wind to build his best test innings.
By early stumps on Saturday he had batted almost six hours, faced 224 balls and had hit 12 fours and one six. He lasted through the shortened first day on which South Africa lost Graeme Smith for 5 when it was 13 and Hashim Amla for 63 when it was 106, after a 93-run second wicket partnership.
New Zealand's bowlers, short of firepower and struggling in difficult conditions, haven't taken a wicket since Amla was out in the 34th over of the innings, 45 overs and more than a day ago.
While Petersen was the rock of the South African innings, Duminy was more attacking and they formed an ideal partnership which left South Africa in a position from which it is unlikely to lose this test.
South Africa leads the three-match series 1-0 after winning the second test at Hamilton by nine wickets. The rain-affected first test at Dunedin was drawn.
Petersen reached his half century on Saturday in 3-1/4 hours, from 124 ball and with five fours and a six. His innings was patient, watchful and painstaking but he was never pinned down by the New Zealand attack.
Duminy's half century, his fourth in tests, came in 123 minutes from 80 balls and with seven fours. He scored more quickly than Petersen but the opener remained the keystone of the partnership.
The most-effective member of New Zealand's three-pronged seam attack was Mark Gillespie who bowled many of his 20 overs into the wind and who had 1-68 by stumps.
Petersen gave one chance, edging a ball from Doug Bracewell just wide of Martin Guptill at second slip when he was 68 and South Africa 188-2. Guptill dived full-length to his right but couldn't hold the chance.
Fine weather is forecast for the next two days, but only South Africa remains in with a serious chance of winning the match.