Playing without key openers Gautam Gambhir and Virender Sehwag, India rode on a brilliant half-century by Rohit Sharma and Suresh Raina’s racy 23-ball 41 to post a competitive 168 for six after skipper Mahendra Singh Dhoni won the toss and elected to bat.
The visitors then returned to restrict South Africa to 147 for nine in the stipulated 20 overs to complete the victory at the Moses Mabhida Stadium.
India and South Africa will next play the five-match one-day series starting at Durban on Wednesday.