Du Plessis (102 retired), opener Dean Elgar (117 retired) and Quinton de Kock (99) hit out against a South Australian XI.
Du Plessis (102 retired), opener Dean Elgar (117 retired) and Quinton de Kock (99) hit out against a South Australian XI on the opening day of the two-day match in Adelaide.
The Proteas were dismissed for 489 on the penultimate ball of the day against the second-string South Australians.
The one notable failure was opener Stephen Cook, who failed for the third time in as many innings on the Australian tour.
Cook was dismissed for a duck, following his scores of five and 12 against a Cricket Australia XI last weekend in a pink-ball day-night match.
But du Plessis, Elgar and de Kock -- who made a century against the CA XI at the Adelaide Oval -- spent valuable time in the middle ahead of the first Test against Australia starting in Perth on November 3.
Du Plessis and Elgar shared in a 179-run partnership for the fourth wicket after the Proteas lost three early wickets.
Hashim Amla (nine) and Rilee Roussow (22) failed to get among the runs. But the two centurions and de Kock made the most of their opportunities.
Du Plessis, who hit 16 fours off 112 balls, was the first to reach triple figures with his second six of the innings.
Elgar, who struck 12 fours and four sixes, got his runs off 143 balls.
De Kock tore into the local bowling attack, hammering his runs off just 94 balls with 13 fours and a six.