In a contest where fortunes swung from one side to another, Bangladesh fought valiantly until the end riding on gritty knocks from Mahmudullah (20) and Towhid Hridoy (37), but could not land the killer punch in the 20th over chasing a modest 114.
With six needed off last two balls, Mahmudullah was caught near the ropes excellently by Aiden Markram off Keshav Maharaj (3/27), who was South Africa’s most successful bowler. The left-arm spinner bowled three full tosses in the final over but the Bangladesh batters were not able to put them away to end at 109 for seven.
Anrich Nortje (2/17) continued to make the most of his form and Kagiso Rabada (2/19) and Marco Jansen (0/17) provided strong support.
South Africa had recovered to post 113 for six after opting to bat on what has proved to be a challenging surface.
Tanzid Hasan (9) perished early in the run chase after hitting a couple of fours while neither their skipper Najmul Hossain Shanto (14 off 23) nor Litton Das (9 off 13) could convert starts.
Shakib Al Hasan (3) too was beaten by Nortje’s pace when the right-armer bowled one short and the Bangladesh all-rounder mishit to lob one high in the sky.
Struggling at 50 for four, Bangladesh found an excellent partnership between Towhid Hridoy and Mahmudullah, who put on 44 for the fifth wicket to take their side close to the finish line.
Hridoy, who began with a six, did well to absorb the pressure in the company of Mahmudullah.
The pair kept shaving off the target with smart rotation of strike as well as picking up the odd boundary, signalling that the wicket really has rewards for those who were able to alter their approach.
Bangladesh seemed to be cruising towards the target until Hridoy’s dismissal — leg-before off Rabada in the 18th over — changed the complexion of the game.
Earlier in the first half, pacers Tanzim Hasan Sakib and Taskin Ahmed excelled in favourable conditions to help Bangladesh restrict South Africa to a below-par total.
Tanzim (3/18) ran through the Proteas top order in company of Taskin (2/19) while Mustafizur (0/18) too played his part well as Bangladesh produced a collective show despite strong resistance from Heinrich Klaasen (46) and David Miller (29).
Klaasen and Miller looked to revive South Africa from a shaky start with a 79-run stand for the fifth wicket, but the pair could never really accelerate on a two-paced wicket on which the Bangladesh spinners also displayed control.
Tanzim struck thrice in his opening burst to leave South Africa reeling at 23 for four inside the first five overs.
After Quinton de Kock (18) showed aggressive intent by hitting the right-arm bowler for a six and a four in the initial exchanges, Tanzim made immediate amends to his line and length and hit Reeza Hendricks in front of the stumps for a golden duck.
In fact, it was his simple yet effective tactics of bowling at the wickets paid high dividends as Tanzim cleaned up South Africa captain Aiden Markram (4), who missed a straight one with his bat coming down a bit awkwardly.
Tristan Stubbs (0) had done a fine job of rebuilding the innings for South Africa in their last outing against the Netherlands, but the right-hander too had a soft dismissal to endure.
Klaasen hit a couple of sixes upfront against Bangladesh spinners to push them back while Miller was content in rotating the strike. However, he was cleaned up by Taskin late in the innings after a 44-ball knock, studded with two fours and three sixes.
Klaasen and Miller did find run-scoring difficult on the Nassau County pitch since they were forced to curb their attacking instinct.