Graeme Smith and Jacques Kallis' 200-run stand for the third wicket has put South Africa in a commanding position against New Zealand at stumps on day three of the test in Dunedin.
The experienced duo both racked up centuries on the back of some rock solid defence, unshakable patience and a fair amount of ability to help the tourists reach 268 for three.
Having earlier dismissed New Zealand for 273, the Proteas lead by 233 runs. And with the wicket expected to get lower and slower, the home side is not in enviable position.
Smith's 24th century came off 201 deliveries and was demonstration in superb defence and a great ability to work the ball into the leg side. He was eventually bowled for 115 by Doug Bracewell, who was the pick of the New Zealand bowlers with three for 53.
Kallis was arguably more authoritative, although he was slower to reach three figures with his 100 coming off 219 balls.
It was his 42nd test hundred and he has now moved ahead of Australia's Ricky Ponting and into second place on the list of leading century-makers.
He trails only India's Sachin Tendulkar who has 51 test 100s.
Kallis played some superb on-drives and slapped a struggling Tim Southee through square and mid-wicket for consecutive boundaries and was undefeated on 107.
New Zealand made a bright start to the morning with Trent Boult slapping 22 runs off the second over of the day. Vernon Philander watched bemused as three sixes disappeared in the general vicinity of wide midwicket.
And Chris Martin got a huge cheer when he pushed the ball into the covers and set off for a quick single only to get a bonus four runs when Alviro Petersen's throw missed the stumps and carried all the way to the rope.
Martin was caught at short leg shortly after but New Zealand's lead had grown from five runs to 35.
The home side then picked up two quick wickets. Petersen survived a couple or promising shouts including a decision which was referred to the third umpire. Regardless, he insisted with an aggressive approach and came unstuck with a lofted drive to mid-off.
Bracewell was celebrating again moments later when Hashim Amla got an edge and Martin Guptill napped a fantastic diving catch, scooping the ball up off the grass tops.