Leading the standings by a point over Australia and a further point ahead of hosts the West Indies, a victory for South Africa today will confirm their place in the final at the same venue in seven days' time.
Their captain, A.B. de Villiers, is appearing in his 200th ODI for his country.
Mindful of a pitch that is expected to be more helpful to the fast bowlers than at the previous venues in Guyana and St Kitts, the Proteas
have brought in tall fast bowler Morne Morkel for his first match of the tournament at the expense of left-arm wrist-spinner Tabraiz Shamsi.
Australia have adopted similar tactics by bolstering their pace armoury with the return of Mitchell Starc, in keeping with the policy of alternation between himself and Nathan Coulter-Nile, and also selecting Scott Boland for his first appearance in the competition. Glenn Maxwell returns to the line-up in the middle-order at the expense of Travis Head after missing the last two matches at Warner Park.
Teams: Australia - Steve Smith (captain), Aaron Finch, Usman Khawaja,
George Bailey, Glenn Maxwell, Mitchell Marsh, Matthew Wade (wicketkeeper),
James Faulkner, Mitchell Starc, Scott Boland, Josh Hazlewood.
South Africa - A.B. de Villiers (captain), Hashim Amla, Quinton de Kock (wicketkeeper), Faf du Plessis, J.P. Duminy, Farhaan Behardien, Chris Morris, Wayne Parnell, Kagiso Rabada, Morne Morkel, Imran Tahir.
Umpires: Kumar Dharmasena (SLK), Joel Wilson (WIS)
Match Referee: Jeff Crowe (NZL)