Mitchell Johnson broke South Africa's back with seven wickets, including a late five-wicket burst to hand Australia a distinct advantage in the first cricket Test in Perth on Thursday.
South Africa were cruising along nicely at three for 110 before Johnson (7-42) bowled a lethal spell for his career best figures, to leave the visitors at 243 for eight at stumps on day two.
Australia's lower-order batsmen showed tenacity and took the first innings score to a respectable 375 with the last pair of Jason Krezja (30 not out) and Peter Siddle (23) adding 34 runs Thursday. Makhaya Ntini finished with figures of 4-72.
South Africa is now 132 runs behind Australia's first innings total with Mark Boucher (2) and Dale Steyn (1) at the crease.
Johnson provided Australia an early breakthrough when he dismissed opener Niel McKenzie with 16 runs on board.
Skipper Graeme Smith (48) and Hashim Amla (47) added 90 runs. The duo played some delectable strokes and looked set for a big partnership. Krezja removed Amla and Johnson dismissed Smith in quick succession.
Amla was bowled through the gates as he misread a well-flighted Krezja delivery and in the next over Smith dragged Johnson onto the stumps.
Jacques Kallis (63) and AB de Villiers (63) came together to stich another partnership as South Africa took tea at 151 for three. The duo with a 124-run stand brought South Africa back on rails but Johnson had other plans.
Johnson grabbed five wickets for 2 runs in 20 balls in front of his home crowd as he stunned the visitors. The five-over burst from Johnson could be the deciding factor in the absorbing contest that has swayed both ways.
The rot started with both de Villiers and Kallis departing to edges to Brad Haddin in consecutive overs.
Jean Paul Duminy (1) was unlucky to be ruled caught behind off his arm and Morne Morkel (1) and Paul Harris (0) spooned catches to Krejza. Morkel was caught at leg gully while a slower ball undid Harris.
Australia 375 all out (Simon Katich 83, Andrew Symonds 57, Michael Clarke 62; Makhaya Ntini 4-72).
South Africa 243 for eight (Jacques Kallis 63, AB de Villiers 63, Graeme Smith 48, Hashim Amla 47; Mitchell Johnson 7-42).
Australia 1st innings: (overnight 341 for 9) Krejza not out 30; Extras: (lb 7, w 3, nb 5) 15; Total: (all out in 98.5 overs) 375;
Fall of wkts: 1-14, 2-14, 3-15, 4-164, 5-166, 6-259, 7-298, 8-303, 9-341, 10-375; Bowling: Ntini 19.5-1-72-4, Steyn 23-4-81-2, Kallis 15-2-65-0, Morkel 20-1-80-2, Harris 21-2-70-2
SA 1st innings: McKenzie c Krejza b Johnson 2, Smith b Johnson 48, Amla b Krejza 47, Kallis c Haddin b Johnson 63, AB de Villiers c Haddin b Johnson 63, Duminy c Haddin b Johnson 1, Boucher batting 2, M Morkel c Krejza b Johnson 1-11-10-0, Harris c Krejza b Johnson 0-3-3-0, Steyn batting 1; Extras (lb 5, w 4, nb 6) 15; Total (for 8 wkts in 78 overs) 243;
Fall of wkts: 1-16, 2-106, 3-110, 4-234, 5-237, 6-238, 7-241, 8-241; Bowling: B Lee 16-3-41-0, Johnson 18-2-42-7, Krejza 25-2-102-1, Siddle 16-5-43-0, Symonds 3-1-10-0.