Australia made a tentative start after winning the toss and deciding to bat in the first Test against South Africa at Kingsmead on Thursday.
The tourists were soon reduced to 39 for 2, with opener Cameron Bancroft making just five before being caught behind off Vernon Philander.
Usman Khawaja then added just 14 before also being caught by wicket-keeper Quinton de Kock off the bowling of Kagiso Rabada, before captain Steve Smith came in to steady the ship with David Warner.
Explaining his decision to bat, Smith said: "The pitch is pretty hard. It might skid on then slow down later. We want to post a good first-innings total and put them under pressure."
South Africa made two changes from the side that lost to India in the third Test in Johannesburg in January.
Left-arm spinner Keshav Maharaj and batsman Theunis de Bruyn replaced fast bowler Lungi Ngidi and all-rounder Andile Phehlukwayo.
"We've gone with seven batsmen," said South African captain Faf du Plessis. "Against this Australian bowling line-up we wanted a good solid batting line-up."
There were no surprises in the team that Australia announced on Wednesday. It was unchanged from the side that completed a 4-0 Ashes series win against England in Sydney in January.
It included three fast bowlers, backed by off-spinner Nathan Lyon and seam bowling all-rounder Mitchell Marsh.
South Africa: Faf du Plessis (captain), Dean Elgar, Aiden Markram, Hashim Amla, AB de Villiers, Quinton de Kock (wkt), Theunis de Bruyn, Vernon Philander, Keshav Maharaj, Kagiso Rabada, Morne Morkel.
Australia: Steve Smith (captain), David Warner, Cameron Bancroft, Usman Khawaja, Shaun Marsh, Mitchell Marsh, Tim Paine (wkt), Pat Cummins, Mitchell Starc, Nathan Lyon, Josh Hazlewood.
Umpires: Kumar Dharmasena (SRI), Sunderam Ravi (IND)