Quinton de Kock smashed his fourth century of the World Cup and Rassie van der Dussen also hit a ton as South Africa made 357-4 against New Zealand at Pune's MCA Stadium on Wednesday.
In a highly-anticipated contest days after their countrymen faced off in the Rugby World Cup final, De Kock led the way with a 116-ball 114 while Van der Dussen exploded late on to score a 118-ball 133 for his second ton of the tournament.
The Proteas built on the pair's 200-run partnership with 119 in the last 10 overs as David Miller put the New Zealand bowlers to the sword with a blistering 53.
South Africa started steadily after New Zealand skipper Tom Latham won the toss and opted to bowl, as they shrugged off the dismissal of captain Temba Bavuma (24) and flexed their muscles with top-scorer De Kock going past 500 runs in the tournament.
De Kock, who will retire from the 50-overs format after the tournament, milked the Black Caps bowlers in a flawless innings and reached his century with a massive six over long-leg off Jimmy Neesham before looking to raise the tempo. He hit two more boundaries but offered a catch to Glenn Phillips at backward point as Tim Southee (2-77) took his first wicket on his return to competitive action after having right thumb surgery in September.
Tim Southee then castled Van der Dussen on a day of little joy for the New Zealand bowlers, who had lost seamer Matt Henry due to a right hamstring problem midway through the innings.