ICC World Twenty20 Group A, Cape Town:
South Africa 146-3 (18.5 ovs) bt Bangladesh 144 (19.3 ovs) by 7 wkts
Smith gave South Africa a solid start to their reply
Hosts South Africa made it two wins out of two in Group A, defeating Bangladesh by seven wickets in Cape Town.
The Tigers made an explosive start, passing 50 in the fourth over, but had already lost three wickets by then.
Aftab Ahmed hit 36 from 14 balls with five fours and two sixes but they were all out for 144 with three balls left.
Graeme Smith struck some fierce shots in 41 and Albie Morkel fired two sixes in his 41, before Justin Kemp sealed victory in the 19th over with a six.
With both sides having already qualified for the next phase, there was technically nothing in the contest but South Africa were no doubt mindful of their defeat by Bangladesh in the World Cup earlier this year.
Makhaya Ntini struck with his first ball, a trifle fortunate to get an lbw with his wide angle of attack, but was then hoisted for two sixes as Aftab Ahmed stepped down the track fearlessly.
Tamim Iqbal, who hit two fours in the opening over, miscued to mid-off but the shots kept coming.
Mohammad Ashraful flicked his first ball for six, turned in his crease to steer the next one over short fine-leg for four but then spliced the third ball to mid-on.
Having struck Morne Morkel's opening delivery for four, Aftab lost his off-stump to the next.
Aftab gave Bangladesh hope but too many batsmen fell recklessly
JP Duminy, brought in for the rested Herschelle Gibbs, swooped in from mid-off and hit the one stump on view with an underarm throw as South Africa impressed in the field.
He also took an oustanding catch diving backwards in the covers.
Faced with little more than seven an over to chase - a virtual cruise in Twenty20 - left-handers Smith and Duminy were content to ensure wickets remained intact.
Duminy, not the most aesthetic of batsmen, flat-batted the first six of the innings in the ninth over, before trapped next ball attempting another bludgeon to leg.
The burly Albie Morkel swiped a six into the second tier at mid-wicket, measured at 99 metres, two behind Chris Gayle's mighty 101 which currently leads the unratified longest hit competition
Smith offered a technical chance when 37 but bowler Farhad Reza was relieved to emerge with no broken bones, and the captain brought up the 100 next ball with another brutal drive down the ground.
He top-edged to leave a requirement of 37 from 38 balls and though the Tigers showed admirable determination to stay in contention almost until the end, Kemp dashed their hopes with a mighty swing over mid-wicket.
South Africa captain Graeme Smith: "It's two good wins for us, Bangladesh was always going to be a tough one. They came out with nothing to lose and played really aggressively.
"I liked the way we adapted and it was a good run chase, we did what we needed to."
Bangladesh captain Mohammad Ashraful: "We were 15-20 runs short but we really worked hard