Courtesy Rahane's unbeaten 100, India declared their second innings at 267 for five.
In their bid to bat out for a draw, South African skipper Hashim Amla decided to defend anything and everything that came his way and added only 35 runs in 34 overs with opener Temba Bavuma (30).
Such was their defensive mindset that they scored at a rate of less than a run per over for the better part.
Amla's 46 balls to get off the mark is the third most balls consumed after Stuart Broad (62 balls vs NZ in 2013) and Grant Flower (51 balls vs NZ in 2000).
Also Read
Bavuma also showed resilience facing 104 balls which included three streaky boundaries and a six off Ravichandran Ashwin.
This is the first time that two South African batsmen in this series have played 100 balls each in a single innings. This was after opener Dean Elgar (4) was removed by Ashwin, who was introduced in the fourth over. The Proteas still need 476 runs for an improbable win.
With his sixth hundred in the longest format, Rahane also joined the elite list of Indian cricketers, who have reached the three-figure mark in both innings of a Test match.
(REOPENS DEL 37)
Rahane batted like a man possessed as he changed gears from cautious to attacking with effortless ease. Kyle Abbott was cut to the boundary while he used the pace of a short delivery from Morne Morkel to guide it over third-man fence for six.
While he played 152 balls for his 52 yesterday, he took another 54 balls in the morning session to complete his remaining 48 runs.
Wriddhiman Saha (23 not out) added 56 runs in only 14.1 overs with Rahane.
Skipper Virat Kohli (88) must be a disappointed man as he missed out on a well-deserved 12th Test hundred, managing to add only five runs to his overnight score of 83.
In all, Kohli faced 165 balls hitting 10 boundaries as Rahane continued without much fuss.
The Rahane-Kohli duo added 154 runs for the fifth wicket, which is by far the highest partnership for any wicket among the either teams in the series.