Chasing 266 to record its first ever series-win on South African soil, India were tottering at 137 for six in 31.3 overs, 50 runs behind the par score, when rain stopped play.
When play resumed after more than an hour's break, India were set a revised target of 260 from 46 overs but only eight balls could be bowled and skies opened up again, leading to another forced break.
Play never resumed again and the umpires called off the match with South Africa emerging winners. Both the sides will now travel to Centurion for the fifth and final match.
Virat Kohli waged a losing battle all alone as the other Indian batsmen surrendered abjectly.
Image: India's batsman Virat Kohli, left, watches his shot as South Africa's bowler Robin Petersen, right, attempts fielding own bowling during the fourth One Day International cricket match at the St George√É¬ēs stadium in Port Elizabeth, South Africa on Friday Jan. 21, 2011.