Simon Harmer claimed four morning wickets as Australia went to lunch at 411 for eight on day three of the third and deciding Dafabet Test at YesPlay Newlands in Cape Town on Thursday.
The visitors began the day in a very strong position, 330 for four, a lead of one run with six sticks in the bank, but Harmer (37-6-104-4) removed both set batters, Josh Inglis (102) and Alex Carey (80) while Kagiso Rabada (23-1-98-1) had Australia captain Pat Cummins trapped in front without scoring to leave the current World No. 1 side 82 runs ahead.
Inglis started the day on 85 and added just 17 runs to his overnight total before edging through to wicketkeeper Ryan Rickelton, but not before going to his second Test century which included 11 boundaries and two sixes. Harmer then accounted for Carey, well caught by Aiden Markram at first slip after 168 balls and seven fours.
Rabada then finally found success in removing Cummins before Gerald Coetzee (19-4-71-1) also claimed his first wicket in the Test, getting Mitchell Starc slashing at a delivery without foot movement and edging through to Rickelton.
Cooper Connolly and Nathan Lyon were then resolute, despite a few edges and shouts for lbw, as the pair trundled their way to the luncheon interval with an unbeaten stand of nine, with Connolly on 20 and Lyon on one.
Cummins had won the toss on the first morning and asked South Africa to bat first, and the decision looked to backfire as South Africa posted an opening stand of 158 between Markram (78) and Marques Ackerman (95).
Despite David Bedingham (50) and Marco Jansen (52) notching up half centuries and a 41 from Rickelton, Starc(16.3-2-72-6) blew the South African lower order away with the new ball under cloudy skies. Starc's spell of 6-12 in six and a half overs dismantled the Proteas shortly before the close, 329 all out.
Nathan Lyon (2-72), Connolly (1-41) and Josh Hazlewood (1-59) contributed to South Africa's downfall.
Having began the second day with an opening stand of 58 between Travis Head (41) and Matt Renshaw (74), Harmer struck twice before lunch, removing Head and Marnus Labuschagne (0) to leave the visitors on 90 for two.
South Africa again only tasted success twice in the middle session, as Jansen (18-5-55-2) had Renshaw caught behind and then Cameron Green (65) caught in the slips by Harmer.
The evening session belonged solely to Australia as Inglis and Carey added 145 unbeaten runs for the fifth wicket to put their side one run in the lead by the close. Carey had struck four boundaries in his 126 deliveries to head off unbeaten on 51 while Inglis was more aggressive, striking nine fours and two sixes from 111 balls to end the day on 85.
With the series poised on a knife-edge, Australia would have looked to press home their advantage this morning but Harmer, Rabada and Coetzee saw to it that the hosts would enjoy their lunch a little more than they would have enjoyed their breakfast.