South Africa wrapped up the Zimbabwe innings for 136 in 37.2 overs, comprehensively outplaying their neighbours to win the first one-day international by 165 runs.
After battering 301 for seven in their 50 overs, South Africa bowled and fielded efficiently.
Zimbabwe will be disappointed none of their batsmen managed topass 30, captain Tatenda Taibu scoring 28 and opener Stuart Matsikenyeri 25.
Fast bowler Makhaya Ntini took three for 42 for South Africa after rapid half-centuries by Graeme Smith (50), Adam Bacher (56) and Jacques Rudolph (50) had set up their total, aided by 49 from Mark Boucher.
South Africa's second-string attack, missing Shaun Pollock, Andre Nel, Charl Langeveldt and Jacques Kallis, was still too much for Zimbabwe's batsmen to handle.
At 55 for four in the 13th over, the match was firmly in the home side's control and Albie Morkel virtually sealed matters when he took two wickets in the 20th over.
Zimbabwe were 75 for six and although Taibu and Sean Williams added 35 for the seventh wicket, the last three wickets were taken for 26.
South African captain Smith said: "I don't know if it was because of all the rain the past week, but the facilities weren't great.
"The pitch was slow and up and down. A lot of balls kept low and others took off from the cracks and Mark Boucher played superbly to get us to 300. "
The second one-dayer is on Sunday in Durban where Zimbabwe will be heartened that Heath Streak is back in the fold after news that he has signed a contract to play for his country again after a year-long exile.
