Johnson's magnificent seven stun South Africa

South Africa 8 for 243 (de Villiers 63, Kallis 63, Johnson 7-42) trail Australia 375 (Katich 83, Clarke 62, Symonds 57, Ntini 4-72) by 132 runs
Scorecard and ball-by-ball details
How they were out

Mitchell Johnson ruined South Africa's brave pushes for safety with a dramatic seven-wicket haul that included five late breakthroughs as the visitors spluttered to 8 for 243 at stumps. Jacques Kallis and AB de Villiers had almost put South Africa in a comfortable position when Johnson surged to career-best figures and put Australia, who posted 375, on top during another fascinating arm-wrestle for ascendency.

In an incredible finish to the day Johnson grabbed 5 for 2 in 20 balls to wow his new home crowd and stun the visitors, who were happy until he arrived to deliver five venomous overs. de Villiers and Kallis had both raised half-centuries and thoughts had turned to the size of South Africa's lead. Johnson stopped all that with 7 for 42 off 18 overs and ensured it was Australia who finished the second day of a gripping contest on top.

South Africa were 3 for 234, following a 124-run stand between de Villiers and Kallis, but they both departed to edges to Brad Haddin in consecutive overs to start the nail biting in the visiting dressing room. Soon there were uncontrollable shakes as the debutant JP Duminy was unlucky to be ruled caught behind off his arm and Morne Morkel and Paul Harris fell to takes by Jason Krejza. This is a game that changes as quickly as a child's mind.

The South Africans have had dreams like this before, where they walk into gardens of success and don't notice the only cliff. How they recover from these brutal blows will determine how successful they are for the remainder of the series. They were not the only ones who were shocked.

Perth is a fitting venue for a performance like this. It was Dennis Lillee, the WACA hero and association president, who spotted Johnson as a teenager in Townsville and started his representative journey. They spoke before the match about how to bowl on the surface and Johnson listened. In the off-season Johnson, a Queenslander, moved to Western Australia so he could be closer to his girlfriend. Now the ground has another hero of speed.

He was operating well above 140kph, gaining bounce and tricking the right-handers with his subtle arc away. de Villiers and Kallis both fell for that, while the fending Duminy was undone by speed. Showing he wasn't all brawn, Johnson used a slower ball to Morkel that was popped to Krejza and then forced Harris to clip to leg gully. Exhausted by his effort, he needed the trainer for some muscle problems, but his body was probably overwhelmed by such instant success.

Once again the day swayed like a swing, with Australia starting and finishing with whoops of joy. In between South Africa were the ones having most fun, especially with de Villiers and Kallis combining so well. Following the loss of Graeme Smith and Hashim Amla in nine deliveries, which cut South Africa to 3 for 110, the middle-order pair first hit back before tea, and then consolidated after the break.

Johnson's first dismissal, of Neil McKenzie, relied on a horrible error and an ugly pull, but South Africa moved forward with confidence. Smith and Amla seemed to be setting the perfect platform until the trend of the opening day repeated when Australia hit back with two wickets before lunch. Krejza provided the speed bump to the 90-run partnership when Amla tried to turn a well-flighted, spinning delivery to the legside and was bowled for a breezy 47 from 67 balls.

In the next over Smith, who was battling a nagging left elbow problem, was attempting to continue his acceleration by driving at a wider delivery from Johnson, but he played on to his leg stump for 48. Both settled batsmen departed in quick succession, something that de Villiers and Kallis copied.

The pair went in the same way for the same score of 63. Separating de Villiers and Kallis was difficult as they played similar innings, mixing solid defence with punishment of loose balls. While they appeared subdued at times, they were always managing to switch the strike in a combination that looked unbreakable until Johnson intervened.

de Villiers flexed early by swiping Krejza, playing his first Test at home, for six to midwicket and in the period before tea Kallis was also more expansive than Australian audiences were used to seeing him. Kallis lofted Krejza over his head and after tea welcomed Andrew Symonds' medium pace with back-to-back cover drives. He also belted Krejza over the rope and was responsible for some of the treatment that led to the offspinner's 1 for 102 off 25 overs.

Following a burst of boundaries, the batsmen would switch back into a more cautious mode and it was an effective ploy. Krejza was loose at times and occasionally severely threatening, but mostly the Australians were thankful for the regular sprints provided by the tireless and enthusiastic Johnson. Using sliding deliveries and benefiting from the surface, Johnson provided the danger that neither Brett Lee nor Peter Siddle could produce. He will remain a crucial man throughout the series.