Cape Town:Morne Morkel threatened to derail India's chase with an inspired performance but it was India who held their nerve, and took a 2-1 lead in the series.
Yusuf Pathan swung the game India's way with three brutal hits and Harbhajan Singh sealed the win with two violent game-breaking hits.
India were 104 runs adrift of the target when Yusuf cemented his world-cup spot by biffing Johan Botha for three sixes in an over to push India ahead.
When he fell, 39 runs short of the target, Harbhajan crashed Wayne Parnell and Morne for stunning sixes at vital moments of the chase to clinch the game, with 10 balls to spare.
India had lost five wickets and looked down for the count on a sluggish pitch where stroke making wasn't easy when Yusuf launched a violent assault on Botha. He muscled three sixes, the last one flew out of the stadium, to loot 19 runs in the 30th over.
Yusuf added 75 runs with Suresh Raina, who threw his wicket to a wild shot in the 37th over, before falling in the 40th to a stunning catch by Morne, who arched back to pouch an upper cut over his head at third man.
His dismissal put South Africa ahead but Harbhajan seized the moment. He added 26 runs with Zaheer Khan before stitching together another 15 with Aashish Nehra to take India home.
Control was a loose concept tonight. Whenever South Africa got ahead, India pulled them back and whenever India had the edge, South Africa wrestled it back. In the end Yusuf's innings proved the difference.
Yusuf's strength is his mental tenacity. His short-ball woes are well documented but he rarely lets a delivery in his hitting arc go unpunished. Unlike Raina, he doesn't hang back and expect bouncers every ball and today, too, that temperament was on display.
Until that game-breaking 30th over bowled by Botha, it was South Africa who were ahead, courtesy Morne. He dismissed the in-form Virat Kohli to push South Africa ahead, later knocked out Raina to resuscitate fading hopes, and grabbed a stunning catch to dismiss Yusuf but still had to end up on the losing side.
In hindsight, South Africa will feel they were 25 runs short. A shaky Graeme Smith was the reason South Africa dawdled at the start, and it was also due to him that they stayed afloat for a while.
However, his dismissal in the 23rd over left them wobbling at 90 for 4,but JP Duminy and the debutant Faf du Plessis showed admirable maturity to revive the innings and give it respectability.
du Plessis' serenity under pressure was reflected by the fact that he hit his first boundary - a crisp cut off Yuvraj Singh- after he had reached 39. It's not a criticism but a tribute to his mature approach that there were just two shots that stayed in the mind: The first was that cut shot and the second, which came after his fifty, was a skilful shot that hinted at a larger repertoire that he had deliberately held under check. He went down the track to Munaf Patel, adjusted to the slower one, and managed to punch it on the up and over mid-off.
Mostly, he kept things risk-free like an experienced pro and dealt in calculated nudges and pushes. He brought up his fifty with a dab to the on-side and brought up the hundred of the partnership, in the 44th over, with swat-pull through midwicket.
For his part, Duminy, who set off the collapse at Bull Ring by holing out to long-on, too remained patient and worked the angles. He flicked and square drove and adjusted to the slow pace.
The ball didn't come on to the bat neatly but he waited on the front foot, to steer and dab his way through the difficult period. However, both batsmen fell, in the space of four deliveries, after they took the Powerplays in the 45th over and South Africa crumbled in the end overs, losing their last six wickets for 20 runs.
It was a torrid time for Smith, first against Zaheer, and soon against everyone. However, perhaps due to the brittle nature of the lower order, Smith never dared to hit his way out of trouble.
During a sequence of 11 deliveries from Zaheer when he was beaten nine times, Smith actually looked at the bowler and smiled. There was a touch of embarrassment in it but it was also a smile of a man who seemed to have accepted the situation he was in; he chose to graft and was willing to look ugly from then on.
Considering what happened in Johannesburg, it was perhaps the right thing to do as his team needed its leader to fight. Inspired by his grit, Duminy and du Plessis batted with care to propel South Africa but Yusuf and Harbhajan had other ideas.