Play was due to start on schedule after a brief rain shower delayed the toss by 10 minutes.
It is the first international match to be played at the new stadium, outside the capital Georgetown, but the pitch looked in good condition.
Sri Lanka captain Mahela Jayawardene said he expected the pitch to be similar to those normally found in Sri Lanka.
South Africa, needing a win to get their campaign back on track after losing against Australia in St Kitts Saturday, brought in left-arm spin bowler Robin Peterson in place of batsman Ashwell Prince.
Seam bowler Farveez Maharoof returned for Sri Lanka in place of Dilhara Fernando.
Sri Lanka already have two Super Eight points following a win over fellow group qualifiers Bangladesh.
The weather was overcast, hot and humid with a possibility of showers by midday followed by a brighter afternoon.
South Africa: Graeme Smith (capt), AB de Villiers, Jacques Kallis, Herschelle Gibbs, Mark Boucher (wk), Justin Kemp, Shaun Pollock, Robin Peterson, Andrew Hall, Charl Langeveldt and Makhaya Ntini.
Sri Lanka: Mahela Jayawardene (captain), Upul Tharanga, Sanath Jayasuriya, Kumar Sangakkara (wk), Chamara Silva, Tillakaratne Dilshan, Russel Arnold, Farveez Maharoof, Chaminda Vaas, Muttiah Muralitharan and Lasith Malinga.
Match Officials: Umpires: Steve Bucknor (WI), Daryl Harper (Aus) and Third umpire: Mark Benson (Eng). Match Referee: Jeff Crowe (NZ)