Faf du Plessis looked a goner when he was on 33 and did not offer a shot to Michael Clarke. Billy Bowden gave him lbw. He reviewed immediately and replays showed that most of the ball had pitched outside leg. The ball had turned and probably would have hit off stump but that did not matter.
Two overs later, Clarke thought he had du Plessis lbw again, on 37, and so did Billy Bowden. But again, DRS was called on. The ball had pitched in line but it had not made any contact with du Plessis' pad or boot. Even without Hotspot, it was clear that he had hit the ball. The white mark was eventually visible and du Plessis survived again.
After giving du Plessis out twice incorrectly, Bowden was not going to take another chance. When Nathan Lyon appealed for lbw, Bowden was unmoved and this time Clarke turned to technology. The ball turned a significant amount and the tracker showed the bounce would have carried it over the stumps. On 48, Du Plessis was given another life and he made it count.
It was a tough chance, but if Australia needed to win the Test they had to take it. Matthew Wade was standing up to Ben Hilfenhaus and had very little time to react to du Plessis' thin edge. In the last over before tea and du Plessis was on 94.
After all of that, du Plessis saw off ten overs and one ball after tea before he was finally able to raise his bat. An understated drive through cover and two jogged runs made him the fourth batsman to score a hundred on debut for South Africa, and the first to have a half-century and century to his name. Du Plessis raised the bat demurely, acknowledged the dressing room and gave Jacques Kallis a bear hug. There was no leaping or shouting, just quiet recognition. Much was left to do.
Du Plessis had batted a day and more but it was Peter Siddle who was more spent. After bowling 63.5 overs in the match, he had every right to be. With four minutes to go, Siddle was handed the ball to have one last burst. He looked to the sky, he looked to the ground, he had a few sips of his drink, Ben Hilfenhaus walked him to his mark and then he said something to himself. At the non-striker's end was du Plessis. He barely moved as he watched Morne Morkel take guard and then turned to look at Siddle. Two tired men, one winner.
Firdose Moonda is ESPNcricinfo's South Africa correspondent