Captain Graeme Smith led South Africa to their triumph, smashing an unbeaten 89 from 61 deliveries to steer the host nation past Australia's impressive total of 179-8.
The visitors' score was built around Andrew Symonds' innings of 45 from 26 deliveries.
AB de Villiers partnered Smith in a second wicket stand of 116 in just 12 overs which effectively ended the game, played in Centurion.
In the morning game played at the same venue, Pakistan soundly beat Sri Lanka by five wickets with seven balls to spare after an opening stand of 94 between Salman Butt (51) and Mohammad Hafeez (45).
Jehan Mubarak (42) top scored for Sri Lanka in a modest total of 162-7 but off-spinner Hafeez claimed figures of 2-18 in four overs to prove the worth of clever slow bowling in the shortest version of the game.
Kenya produced the first raised eyebrows of the warm-up weekend with a convincing six-wicket triumph over Test nation Bangladesh after bowling the senior team out for a miserable 116 with 21 balls left of their 20 overs.
BLUSHES SPARED
Opener Tamim Iqbal spared some of Bangladesh's blushes with 56 from 41 balls but veteran Steve Tikolo's carefully paced 36 from 28 deliveries saw the African nation win with a ball to spare.
In Potchefstroom, Scotland once again passed 150 but never looked like defending their score against Zimbabwe.
Skipper Ryan Watson made an impressive 64 from 50 balls to lay the foundations for their 155-6 but Vusi Sibanda (42) and Chamu Chibhabha (43) added 79 for the second wicket to take control of the game which ended with seven balls to go.
New Zealand were soundly thumped by the West Indies at the same venue in the afternoon when they were bowled out for just 115 in reply to a modest 150-6.
Dwayne Smith (47) and Narsingh Deonarine (34) rescued the West Indies from a precarious 56-4 but only two men reached double figures for New Zealand in reply.
Peter Fultom made 51 and captain Daniel Vettori hit 24.
Fast bowler Daren Powell returned an extraordinary analysis of 4-0-4-3 but none of the matches will count towards official records as all teams employed 13, 14 or even 15 men in the warm-ups.
The Twenty20 World Cup begins on Tuesday with South Africa against West Indies in Johannesburg in Group A.
