With Australia looking to ram home their advantage over the Proteas on day three, Inglis brought up his hundred in the first hour by reverse-sweeping Simon Harmer for four on his way to 102.
It had been on day three at Newlands on Australia's last visit that the team fell apart, with the 2018 ball-tampering scandal forever changing the sport at home.
Some eight-and-a-half-years later, Inglis used it as a red-letter day to announce himself as a fixture of the looming transition of this Australian team.
The 30-year-old scored a century on debut in Sri Lanka last year, but this one came in more important circumstances against a more accomplished attack.
With a fractured finger having denied a likely call-up earlier in the series, Inglis' chance only came after Steve Smith failed to overcome a neck injury.
When he strode to the wicket on Wednesday Australia were 3-184 and soon to be 4-185, with the door ajar for South Africa after their first-innings 329.
By the time Inglis was dismissed shortly after scoring his century on Thursday, he and Alex Carey had taken them to 5-370 with the Proteas facing an uphill battle to avoid their first home series defeat in almost six years.
The West Australian went through the gears impressively on Wednesday, fighting through an important period after the tea break early in his innings.
As the evening went he became more confident, cutting well and even pulling Kagiso Rabada for six at one stage.
He was also a picture of a player who knew his game, with only seven of his runs coming down the ground and the vast majority being square of the wicket.
Inglis also swept well, and offered a fist pump when he brought up his hundred before embracing Carey and lifting both arms aloft while holding his bat and helmet.
Ultimately, the celebration was short lived, with Inglis edging Harmer through to wicketkeeper Ryan Rickelton later in the same over.
But by that point Australia not only had control, but an eye to what their future may look like with Matt Renshaw and Cameron Green having also scored 74 and 65 respectively on Wednesday.
All in the side's first Test without one of David Warner, Usman Khawaja or Smith in the team since they were bowled out for 47 in Cape Town almost 16 years ago.
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