Fighting to recover from a hamstring injury in time to try and help save the series for the Proteas, Rabada charged in at full speed for 45 minutes at Gqeberha on Thursday.
The 31-year-old appears increasingly likely to play in Sunday's second Test, with South Africa already confirming they will also make two changes to their batting at St George's Park.
Rabada's prowess was on show early on Thursday, squaring up Proteas' captain Temba Bavuma in a centre-wicket net and constantly whizzing the ball past the outside edge.
The right-armer, who took nine wickets in South Africa's World Test Championship final triumph over Cummins' side at Lord's last year, has taken 58 wickets in all at 21.39 against Australia, holding the second-best record of any quick against the Aussies this century.
Proteas coach Shurki Conrad had earlier this week labelled Rabada the hosts' "Rolls Royce", hoping he'd be ready to hit the highway running.
That spark will be much needed as South Africa fight to save the three-Test series, following their 214-run defeat in the Durban opener.
"The thing that stands out to him is he's competitiveness," Australia's assistant coach Matt Wade, who has worked with Rabada in the IPL, said.
"He takes it to the opposition. He'll be in our face. He'll keep coming for the whole Test match, so we really know that.Â
"Him and (Anrich) Nortje can basically take one quick spot and short spells and really attack as hard if they want to."
It was at St George's Park that Rabada was involved in one of the flash points of Australia's last tour here in 2018, when he collided with Steve Smith after dismissing him.
Rabada was initially suspended for two matches over the contact, before having his punishment downgraded to a fine on appeal.
Beyond Rabada, the Proteas have also made other changes.
Kyle Verreynne is set to be axed but will stay in the squad as reserve wicketkeeper while Ryan Rickelton is handed the gloves.
It marks the first time Verreynne has been dropped since he was called back into the side at the end of 2023, averaging 29.5 and hitting three hundreds in that time.
Marques Ackerman will come into the side and could open on debut after facing Rabada at training on Thursday, leaving Rickelton to drop down the order.
Middle-order batter Charlie Stubbs has also been axed, with Matthew Breetzke to come in and play his third Test and first first-class match since February.
He too could be an option to open.
Stubbs made scores of 32 and 1 in Durban, including being caught out trying to hook Pat Cummins in the first innings just two overs after Wiaan Mulder did similar.
The Proteas must also decide who they will leave out for Rabada, and whether they will stick with two spinners, Simon Harmer and Keshav Maharaj, as they did in Durban.
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