Visiting captain Steve Smith admitted he would have done likewise, though conditions for batsmen are expected to be at their toughest in the first hour of the morning with swing and seam movement available.
"There is a little bit less grass on the wicket than in the previous two tests, on day one we expect it to be a little bit slow and then to start reversing later on," Du Plessis said at the toss.
"The first hour there will be movement. It should speed up in the second innings."
The home side have made two changes from the second test, restoring middle-order batsman Temba Bavuma to the lineup after his recovery from a finger injury, while seamer Morne Morkel comes in for Lungi Ngidi, who was struggling with a toe problem.
Morkel has announced his retirement from all forms of international cricket at the end of this series and is currently on 297 test wickets.
Australia are unchanged from the first two tests, with seamer Mitchell Starc and all-rounder Mitchell Marsh having shrugged off minor niggles.
"I would have had a bat, it looks a really good surface," Smith admitted. "But if there is any movement it will be the first hour this morning, hopefully we can get the ball in the right areas and put South Africa under pressure."
The four-match series is level at 1-1.
Teams:
South Africa: Faf du Plessis (captain), Dean Elgar, Aiden Markram, Hashim Amla, AB de Villiers, Temba Bavuma, Quinton de Kock (wicketkeeper), Vernon Philander, Keshav Maharaj, Kagiso Rabada, Morne Morkel.
Australia: Steve Smith (captain), David Warner, Cameron Bancroft, Usman Khawaja, Shaun Marsh, Mitchell Marsh, Tim Paine (wicketkeeper), Pat Cummins, Mitchell Starc, Nathan Lyon, Josh Hazlewood.
(Reporting By Nick Said; Editing by John O'Brien)
