The three-match series is pegged at 1-1. South Africa won in Lucknow by nine runs and India won in Ranchi by seven wickets.
The toss was delayed by 45 minutes due to a wet outfield. Delhi has experienced heavy rainfall over the past few days, but the game is expected to go on without any stoppages.
The match will begin after a delay of 30 minutes and no overs were lost for Tuesday.
David Miller is leading South Africa as Temba Bavuma and Keshav Maharaj are both sick and out of the match.
Spinner Tabraiz Shamsi is also yet to recover from sickness. Fast bowler Kagiso Rabada has been rested ahead of the T20 World Cup beginning in Australia this week.
South Africa made two changes with left-arm pacer Marco Jansen and allrounder Andile Phehlukwayo coming in for Maharaj and Rabada.
India have not made any changes from Sunday's win.
South Africa need to win this match to bolster their qualification hopes for the 2023 Cricket World Cup to be hosted in India.
The pitch at Arun Jaitley Stadium has proven to be two-paced in the past, with the side batting first gaining the advantage.
India: Shikhar Dhawan (capt), Shubman Gill, Ishan Kishan, Shreyas Iyer, Sanju Samson (wk), Washington Sundar, Shahbaz Ahmed, Shardul Thakur, Kuldeep Yadav, Mohammed Siraj, Avesh Khan.
South Africa: Quinton de Kock (wk), Janneman Malan, Reeza Hendricks, Aiden Markram, Heinrich Klaasen, David Miller (capt), Marco Jansen, Andile Phehlukwayo, Bjorn Fortuin, Lungi Ngidi, Anrich Nortje.
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