India lead South Africa by five points and need to win two matches in order to stop falling behind the Proteas. A 4-1 win for the AB de Villiers-led side will put it second on 113 points with India dropping to third on 112 points, according to an ICC release.
But a 3-2 win for the tourists will mean India will retain second spot on 114 points and South Africa getting the consolation of reducing the gap with the host from five points to two.
Meanwhile, the top three batsmen in the player rankings will also feature in the series.
South Africa ODI captain AB de Villiers holds a 73-point advantage over his compatriot and second-ranked Hashim Amla who, in turn, is 21 points clear of India's Virat Kohli.
Apart from Kohli, Shikhar Dhawan (sixth) and Dhoni (eighth) are the other batsmen who represent the home side inside the top 10 and will be looking for upward movements during the series.