The match had begun awkwardly for the Proteas, with rain reducing the first day to only 12.2 overs and leaving them 20/2 after Boland removed Aiden Markram and Marques Ackerman.
Their early position became even more precarious when David Bedingham and Matthew Breetzke also departed cheaply, leaving SA 40/4.
Temba Bavuma then changed the direction of the Test.
His 179 from 334 balls was the innings around which SA rebuilt, but the captain’s contribution became even more valuable because of the partnerships that followed.
Marco Jansen’s 85 from 100 balls injected momentum into the innings, while Simon Harmer’s career-best 82 from 157 balls showed patience to help take the total to 425/9 declared.
From 40/4, SA had produced enough batting depth to establish a 326-run lead.
Australia never recovered from what followed.
Their first innings lasted only 42.3 overs as they were bowled out for 99, with Jansen taking five wickets, Kagiso Rabada and Wiaan Mulder grabbing two each, while Anrich Nortje claimed one wicket before he left the field with a suspected groin injury not long after.
The collapse was comprehensive, and SA’s decision to enforce the follow-on appeared entirely logical.
Nic Maddinson fell for eight, but Travis Head refused to allow another collapse.
His 121 from 190 balls transformed the second innings, giving Australia aggression and belief, while also consuming valuable overs.
Marnus Labuschagne added 39 from 98 balls, while Matt Renshaw and Beau Webster offered resistance around Head.
By the time Head was dismissed for 121, Australia had reached 209/5 and had forced the hosts to work far harder than the first innings had suggested they would need to.
Boland’s 40 from 166 balls and Alex Carey’s unbeaten 37 represented a different kind of resistance.
They absorbed pressure rather than attacking it, and by tea Australia had dragged themselves to 253/6.
