Victory, which saw India into the second round Super Eights after their seven-wicket win over Afghanistan on Saturday, was built on Raina´s 101 out of a total of 186 for five.[break]
Only West Indies´ Chris Gayle and New Zealand´s Brendon McCullum had previously made centuries at this level.
Raina though had an escape on five when he was caught off a Morne Morkel no-ball.
It was an expensive error by the fast bowler, with left-hander Raina striking five sixes and nine fours in a blistering assault as he reached his century off 59 balls.
Together with Yuvraj Singh (37) he shared a stand of 88 in 10 overs after the pair came together with India 32 for two in the sixth over after they´d lost the toss.
"I was struggling when I came in and I was thinking ´just rotate the strike and when I get an opportunity just go for it´," Raina, whose score comfortably eclipsed his previous best of 61 not out against New Zealand in Christchurch last year, said.
"The main thing for me is to hit the ball well. I´m a very positive kind of person, whenever I get an opportunity I go for it," the 23-year-old added.
South Africa captain Graeme Smith praised Raina´s innings but lamented a lack of control from his attack that saw India pile up a mammoth 75 runs in the last five overs.
"Suresh Raina played a terrific knock and he was able to exploit our lack of accuracy towards the back end, when we played into his hands," said Smith.
"I spoke before the game about little things being important and that no-ball proved costly."
Smith had promised his side would be flexible when it came to their openers but few foresaw the skipper dropping himself down to No 3.
Jacques Kallis, who opened in Smith´s place, was nearly out for a second ball nought when a diving Yusuf Pathan at backward point just failed to hold on to a catch off the bowling of Harbhajan Singh.
Kallis went on to complete a 45-ball fifty with three fours before upping the tempo with two slog-swet sixes off Harbhajan in as many balls.
But a stand of 97 in 11 overs was ended when Smith was run out by Praveen Kumar´s throw to wicketkeeper and India captain MS Dhoni.
Then 118 for two became 128 for three when Kallis fell on 73 after driving leg-spinner Piyush Chawla straight to Ravindra Jadeja in the deep.
South Africa though got the target down to 24 off the last over but left-arm quick Ashish Nehra conceded just nine.
India accelerated in the ninth over when Yuvraj swept spinner Roelof van der Merwe for six. Two balls later, Raina lofted all-rounder Kallis high over wide long-on.
India took 25 runs off fast bowler Rory Kleinveldt´s last over, the 18th, with Yusuf Pathan hitting the first ball for six and then taking a single.
Raina then struck three fours in a row, over long-on, through extra-cover and straight down the ground, before the batsman completed the over with a majestic six, struck off one knee and high over long-off.
Come the last over, Raina was on 95 and Dhoni was facing
But when he got on strike, for the third ball, Raina completing his hundred with a six over midwicket off Albie Morkel before getting out next ball.
Dhoni then ended the innings with a six.
South Africa complete their group programme against Afghanistan in Barbados on May 5.
Australia seal easy win
Australia made an impressive start to their World Twenty20 World campaign with Shane Watson hammering 81 from 49 balls in a convincing victory over Pakistan yesterday.
Australia´s innings ended in bizarre fashion with a five-wicket maiden but their total of 191 was always going to be tough for Pakistan. Despite a lively 41 from Misbah-ul-Haq and 33 off 24 balls from Shahid Afridi, Australia never offered them more than a glimmer of hope.
There was some good bowling, with three wickets each for pacemen Shaun Tait and Dirk Nannes, and outstanding catching from Australia which ensured they kept the upper hand, bowling out their opponents with the final ball.
Along with the resounding display from Michael Clarke´s team, the game will be remembered for a remarkable final over to Australia´s innings, in which left-arm pace bowler Mohammad Aamer picked up three wickets while Mike Hussey and Steven Smith were both run out.
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