De Villiers and Rabada tighten South Africa's grip

Australia 243 and 180 for 5 (Khawaja 75, Rabada 3-38) lead South Africa 382 (De Villiers 126*, Elgar 57, Amla 56, Cummins 3-79) by 41 runs
Scorecard and ball-by-ball details

On the third day in Port Elizabeth, AB de Villiers scored one of the finest hundreds of his Test career and Kagiso Rabada put in another excellent bowling performance. If those two men alone could keep up this form throughout the series, Australia would be hard pressed not to lose their first series in South Africa since readmission. But as the players walked off St George's Park at stumps on day three, they knew that something could be about to change, for Rabada was set to face a Code of Conduct hearing that could rule him out of the rest of the series.

Whatever the case, Rabada had helped put South Africa in a powerful position, claiming three key wickets that left Australia needing a significant lower-order bailout in order to post a competitive target. At stumps, Australia had turned their 139-run first-innings deficit into a 41-run advantage, but the loss of Usman Khawaja to Rabada for 75 late in the day was a major blow. Mitchell Marsh remained at the crease on 39, alongside Tim Paine on 5, and Australia had 180 for 5 and a huge amount of work to do.

After early wickets, Khawaja and Mitchell Marsh had led an Australian fightback with their 87-run partnership. Mitchell Marsh was solid in defence and Khawaja had swept and reverse-swept effectively, also driving handsomely through the off side when given the chance. As a qualified airline pilot, Khawaja could be expected to travel well, but his form away from home has always been a major question mark. Before this innings, his previous nine efforts in Tests outside Australia had produced 26, 18, 11, 0, 1, 1, 14, 6 and 4. Adding 75 to that was good, but Australia needed more.

Khawaja fell in the penultimate over of the day when Rabada angled one in from around the wicket and rapped him on the back leg, dead in front. It was so certainly out that Khawaja, the set batsman with two reviews up his sleeve, had little hesitation in walking off. It capped another fine day for Rabada, who had earlier bowled David Warner for 13 with a superb delivery that nipped in through the gate, and also had Shaun Marsh caught behind wafting aimlessly outside off for 1.

Wickets came from other sources, too. On 24, Cameron Bancroft chopped one on off the bowling of Lungi Ngidi to leave Australia wobbling, and Steven Smith's struggles against left-arm orthodox spin continued when he tickled one behind off Keshav Maharaj on 11. It was the third time from four innings in this series that Smith had been out to left-arm fingerspin, and South Africa will hope they have found a rare weakness in his game.

Earlier in the day, de Villiers seemed to have no weaknesses whatsoever. The 22nd hundred of his Test career and his first in more than three years was also one of his best. In Durban, he had looked in ominous touch but ran out of partners before he could do too much damage; in Port Elizabeth, the lower order stuck with him long enough to get South Africa a healthy lead.

The day had started with South Africa 20 runs in front with three wickets in hand. De Villiers batted brilliantly with the lower order, forging an 84-run stand with Vernon Philander, then a 58-run partnership with Maharaj, and finally a 13-run stand with Ngidi to cap the innings. He finished unbeaten on 126 and has been dismissed only once in this series, when he was run out for a duck in the second innings in Durban, following his 71 not out in the first.

Much as a crafty politician answers not the question asked but the question they wish was asked, de Villiers seemed to face not the ball that was delivered but the ball he wanted to have been delivered. In other words, he was able to score runs from anywhere to anywhere, and struck 20 fours and one six during his 146-ball stay.

His century came from his 117th delivery with a typically inventive stroke, gliding Pat Cummins over the cordon for a boundary. The support that he had was invaluable. Philander made a calm 36 before he was brilliantly snapped up by Bancroft at short leg off Cummins.

Maharaj almost threw his innings away early when he slogged Nathan Lyon over midwicket and Khawaja tried a juggling take, throwing the ball back in as he landed over the rope. Maharaj looked set to walk off, with de Villiers clearly frustrated by his shot selection, but replays showed Khawaja had failed to let go of the ball before his foot was grounded over the rope, and it was ruled a six.

If Maharaj learnt his lesson it was only briefly, for in Lyon's next over he clubbed another six over the leg side, and his 30 off 24 balls proved to be a very handy cameo. In the end, another attempted slog brought his downfall as he was bowled by Josh Hazlewood. Ngidi was the last man out, run out attempting to get de Villiers back on strike. South Africa were all out for 382, with a lead of 139. And de Villiers had played what will likely be the innings that turns the match, if not the series.