Jansen rekindled memories of his days playing domestic cricket at St George’s Park for the Warriors with a devastating five-wicket haul as SA put Australia under enormous pressure.
The left-armer followed his counter-attacking 85 in SA's innings with 5/33 from 11 overs as Australia were bowled out for just 99 in their first innings, leaving them 326 runs behind and allowing captain Temba Bavuma to enforce the follow-on.
The home attack dismantled Australia in the first two sessions, with Kagiso Rabada, Wiaan Mulder and Anrich Nortje providing crucial support as they turned their position into an opportunity to push for victory.
The Aussies resumed their first innings on 3/1 on Wednesday in a match where rain had severely restricted play on the opening two days.
Jansen struck twice, dismissing Head for 14 and Boland for two to follow up Rabada’s removal of Nic Maddinson for a duck on Tuesday.
Nortje, who would later leave the field with a suspected groin injury, removed Marnus Labuschagne for 14, leaving Australia 45/4 and staring squarely down the barrel.
Steve Smith faced 88 balls for his 28, before Mulder removed him.
The tall left-arm Jansen then returned to claim two more wickets in quick succession, dismissing Matt Renshaw for 12 and Alex Carey without scoring.
Webster became Jansen’s fifth victim, caught by Aiden Markram for 13, as Australia slipped to 84/7.
Mulder finished with 2/14 from 9.3 overs, Rabada took 2/33 from 12 overs and Nortje claimed 1/5 from 3.3 overs.
Pat Cummins was the final wicket to fall, caught by Matthew Breetzke off Mulder for seven.
