Ravichandran Ashwin claimed Test-best figures as India consigned South Africa to their first overseas series defeat in the longest format of the game for nine years with a 124-run victory on day three in Nagpur.
South Africa resumed on 2-32 on Friday needing an unlikely 310 to level the four-match series after 20 wickets had fallen on an incredible day two at the VCA Stadium.
The Proteas did offer more resistance against the spin in difficult conditions after being skittled out for only 79 on Thursday, but Ashwin took 7-66 - and match figures of 12-98 - as the they were bowled out for 185 in their second innings.
Off-spinner Ashwin took 5-32 in the first innings and shone again on Friday to move above Stuart Broad as the leading Test wicket-taker this year with 55 and give India an unassailable 2-0 lead with one match remaining.
Captain Hashim Amla and Faf du Plessis held up Virat Kohli's side by making a battling 39 apiece, but Amit Mishra (3-51) also impressed as the top-ranked Test side suffered a first series defeat away from home since losing to Sri Lanka in 2006.
Dean Elgar (18) showed his intent by slog sweeping Ashwin for six, but the spinner trapped him leg before wicket three balls later.
The spinners were not getting as much as turn as they had in the first two days, but Ashwin struck again when the dangerous AB de Villiers (9) was trapped in front to reduce the tourists to 4-58.
Amla and Du Plessis showed character to combine for a resilient stand of 72 for the fifth wicket, with the skipper scoring just two boundaries in a dogged 167-ball knock.
It was Mishra who eventually got the breakthrough, with Kohli catching Amla at gully after the spinner got one to rear up and Du Plessis was bowled before tea attempting to pull the same bowler through midwicket but missing a low delivery.
The writing was on the wall for the Proteas and it was no surprise that it was Ashwin who finished them off in the final session.
Ashwin trapped JP Duminy (19) leg before and then wicketkeeper Wriddhiman Saha took a great catch down the leg side after Dane Vilas (12) gloved one in the same over to secure another five-wicket haul for the in-form spinner.
He then got rid of Kagiso Rabada before finishing off the job by bowling Morne Morkel to claim his best Test figures and wrap up the series with one game to come in Delhi next week.