De Kock ton guides South Africa to thumping victory over Australia
Chasing 312, Australia lost half their wickets for 65 runs and had no answer against Kagiso Rabada (3-33), Marco Jansen (2-54) and Keshav Maharaj (2-30) as they folded for 177 in 40.5 overs with Marnus Labuschagne (46) their only top-order batsman to fire.
South Africa's win was built on a platform provided by De Kock, who made 109 while Markram hit 56 to help the Proteas post 311-7 in 50 overs.
Asked to bat first after Australia captain Pat Cummins won the toss, South Africa made a watchful start and rode their luck before De Kock picked up where he left off in the win over Sri Lanka with eight fours and five sixes in his 106-ball knock.
South Africa skipper Temba Bavuma (35) gained two reprieves as Australia failed to hold onto difficult chances before Glenn Maxwell (2-34) snared him, but the Proteas marched on as De Kock twice hit Josh Hazlewood into the stands in the 23rd over.
Spinner Adam Zampa removed the dangerous Rassie van der Dussen (26) but De Kock continued to plunder runs and brought up his 19th ton by pulling Cummins for a huge six shortly after the pace bowler had dropped Markram when he was on one.
Maxwell bowled De Kock out with one that crept through after hitting the left-hander's bat as he attempted a reverse pull and Markram fell to Cummins after a breezy knock, as the Australian bowlers put the brakes on South Africa's scoring.
Cummins could have had two more wickets but Marcus Stoinis and Mitchell Starc put down chances on a sloppy day in the field but a double strike by Starc (2-53) in the last over kept South Africa from swelling the score.