On a day that could have ended Test careers, a few young ones flourish

The vague suspicion before play on day two of the Cape Town Test was that Australia — out of form, stalked by rumours of disharmony in the ranks, its batting line-up restocked and reshuffled for the umpteenth time — was one more calamitous batting collapse away from the end of an era.

The day of perfectly calm and controlled Test batting that took place instead was no less arresting, and in the context of this topsy-turvy series, far more surprising. For 90 overs, Australia batted diligently, adaptively, intelligently and at changing tempos, building a series of reassuring partnerships that put it in control of the game.

Elevated to the opening slot, Matt Renshaw looked safe as houses. Slotted into Steve Smith's number four position, Cameron Green hit a commanding half-century. Drafted in at the 11th hour, Josh Inglis was closing in on a century by stumps and had dragged Alex Carey along in his slipstream.

It all meant that Proteas attack leader Kagiso Rabada, who probably woke up feeling comfortable with the expectation it would be his day to wreak some havoc — perhaps even end some careers — went wicketless, as did too many of his mates.

Thanks to stands of 126 between Renshaw and Green and an undefeated 145 between Inglis and Carey, Australia reached 4-330 by stumps and walked away probably feeling in the box seat on a pitch offering very little assistance to the bowlers.

The weight of numbers was one thing, the problem-solving another. In two testing periods, South Africa made double-strikes and threatened to blow the game back open, only for the tourists to consolidate and rebuild.

The crunch moments came in the 18th over, when off-spinner Simon Harmer ripped out Travis Head and Marnus Labuschagne, and just before tea, when Renshaw and Green were removed by Marco Jansen in the space of a few overs.

Both times Australia took a deep breath, regrouped and pushed on in the same direction as before.

The only major negative of the day for Australia — although the many unkind souls who wish him bad luck will not view it so — was Labuschagne's duck. Out-of-form players often have a knack for attracting unplayable balls. At the moment, poor old Marnus can make almost anything look unplayable.

For a team that has not produced a single 100-run opening partnership in the past three years, Renshaw's 74 from 139 deliveries was a welcome return to normalcy at the top of the order. In a 58-run stand with Travis Head (41) to start off, the Queenslander was deferential and circumspect, showing they could be a fire and ice combination.

But it was Renshaw's union with Green, which stretched across 32 overs, that provided the most welcome glimpse of the future of this Australian team.

They were a study on contrasts: surely no batsman as big as Renshaw has ever made himself such a small target for bowlers; heavy-footed Green, on the other hand, has the awkward tendency to turn himself into a fast bowler's piñata, swaying and ducking into bouncers, and in this case wearing a few painful body blows from the shorter stuff South Africa threw at him in large doses.

In the latter sense, Green again showed he had guts. And as he got going, his fluent stroke play more than made up for the cobwebs he was destined to display after three and a half weeks without a competitive hit.

As Aiden Markram had treated Pat Cummins's bowling with disdain on day one, Green took it upon himself to take down Rabada, who has lorded it over Australia in the past.

The killer blow on that front was when Green moved into the 40s with a trio of swivel-pulls that brought six, six and four off consecutive deliveries.

Renshaw, as in his Durban epic, was more watchful and unassuming, content to press, deflect, dab, flick and generally accumulate — precisely the sort of calm, unhurried Test batting Australia has been crying out for in the past two years, and which is the bedrock of the big, defendable totals Australia will need to post when it can no longer rely on its brilliant but aging bowling unit.

As well as re-emphasising Labuschagne's redundancy, the Renshaw-Green partnership might also, in the wash-up, accelerate the conversation about how Australia tactfully moves on from the Smith and Labuschagne era.

What more is there to say about Marnus at this point? Harmer, who weeded him out this time, is a canny bowler and has proved himself a big-moment performer in this series. But geez, his wicket ball this time was not exactly a jaffa.

Labuschagne shuffled back to what might otherwise have been a half-volley, pushed at it with hard hands, his slicing bat plane again a horror story, and Markram gobbled the edge at slip.

And what Labuschagne had made look impossible in that brief and tortured innings was, by the end of the day, looking entirely straightforward thanks to Inglis and Carey, undefeated on 85 and 51 respectively.

Loose and a little too eager to play his shots earlier in the series, Carey took a leaf out of Renshaw's book with nudges, nurdles and strike rotation. Inglis, whose finger injury prevented even net sessions for most of the past two weeks, clobbered nine fours and two sixes to poleaxe a tiring Proteas attack.

Tomorrow, both or either batsmen could feasibly take the game and the series away from South Africa in the space of an hour or two. But then, we've said that before, haven't we?