Both India and South Africa have two points from their two Group B matches and the winner at The Oval will advance to the semi-finals while the losers will be eliminated.
For South Africa, all-rounder Andile Phehlukwayo came in for Wayne Parnell.
Holders India went for a spin option as Ravichandran Ashwin made his first appearance in the tournament, coming in for Umesh Yadav.
"Teams generally like chasing, so it gives us a chance to do what we need to do when we come out to bat," Kohli said.
"It depends on what the bowlers offer us. When you bat second, you know what you need to do."
India: Rohit Sharma, Shikhar Dhawan, Virat Kohli (capt), Yuvraj Singh, MS Dhoni (wkt), Hardik Pandya, Kedhar Jadhav, RA Jadeja, Bhuvneshwar Kumar, Ravichandran Ashwin, Jaspreet Bumrah
South Africa: Quinton de Kock (wkt), Hashim Amla, Faf du Plessis, AB de Villiers (capt), David Miller, JP Duminy, Chris Morris, Kagiso Rabada, Andile Phehlukwayo, Morne Morkel, Imran Tahir
Umpires: Aleem Dar (PAK) and Paul Reiffel (AUS)
TV umpire: Richard Illingworth (ENG)
Match referee: David Boon (AUS)