South Africa could only make 120 for seven on a tricky track at the Sir Vivian Richards [ Images ] Stadium with 20-year-old debutant David Miller making 33 from 26 balls and Johan Botha [ Images ] 23 from 22 as they recovered from 59 for five.
However a late run-flurry put West Indies in with a chance, largely thanks to smart batting from Darren Sammy.
With 15 needed off the last over, bowled by Ryan McLaren [ Images ], Sammy scrambled a two, edged a four and then ran four, with two overthrows, as South Africa appeared to lose their composure.
But Narsingh Deonarine was run out attempting a two leaving Jerome Taylor to face the final ball with three to win -- a wide full toss which Taylor chased but could only poke for a single, leaving his team short of the target.
The South African tour of the Caribbean continues on Saturday with the first of five one-day internationals.
G Smith b Taylor 15
L Bosman c Fletcher b Taylor 0
AB de Villiers [ Images ] c Bravo b Sammy 19
J Duminy c Fletcher b Sammy 13
A Petersen lbw b Benn 8
D Miller run out 33
J Botha c Sarwan b Taylor 23
R McLaren not out 2
Extras: (b-1, lb-4, w-2) 7
Total: (for 7 wkts in 20 overs) 120
Fall of wickets: 1-6, 2-27, 3-42, 4-57, 5-59, 6-116, 7-120
Bowling: Roach 4-0-24-0, Taylor 4-1-15-3, Benn 3-0-26-1, Bravo 4-0-20-0, Sammy 4-0-16-2, Pollard 1-0-14-0.
C Gayle lbw b Steyn 0
A Fletcher c de Villiers b Morkel 4
D Bravo c Botha b Morkel 40
S Chanderpaul c de Villiers b Botha 29
K Pollard c Steyn b Botha 12
R Sarwan c McLaren b Botha 6
D Sammy not out 12
N Deonarine run out 3
J Taylor not out 1
Extras: (b-5, lb-2, w-5) 12
Total: (for 7 wkts in 20 overs) 119
Fall of wickets: 1-4, 2-9, 3-77, 4-87, 5-97, 6-99, 7-118
Bowling: Steyn 4-0-18-1, Tsotsobe 4-0-28-0, Morkel 4-0-15-2, Botha 4-0-22-3, McLaren 4-0-29-0.