NEW DELHI (AP) Spinner Ravindra Jadeja took 5-30 as South Africa was bowled out for 121 in reply to India's first innings of 334 on the second day Friday of the fourth and final test.
India did not enforce the follow on after gaining a 213-run first-innings lead, but bad light prevented any further play.
Jadeja broke the back of the South Africa middle order after Ajinkya Rahane's stylish knock of 127 put India in command.
''I was determined to get a big score here,'' Rahane said. ''I knew I was batting well in the series, I just needed to spend some time in the middle.''
Pace bowler Umesh Yadav and offspinner Ravichandran Ashwin supported left-armer Jadeja well, taking two wickets each as South Africa, which has already lost the series, folded up in under two sessions.
''We haven't played good cricket in the last couple of weeks, so no excuses,'' South Africa coach Russell Domingo said. ''There was some very good bowling from the Indian side, especially the spinners.''
Jadeja's haul included AB de Villiers, captain Hashim Amla, and Faf du Plessis, as the visiting side again struggled for confidence, technique, and application.
Jadeja bowled cautious opener Temba Bavuma for 22 for his first wicket, and grew in confidence against a diffident batting lineup.
Amla, on 3, was caught behind as he tried to cut a delivery from close to his body, while Faf du Plessis, yet to score, went for a paddle-scoop but Rahane ran around from slip to catch the ball down the leg side.
Jadeja had Dane Piedt caught at slip for 5 at 103-8, while de Villiers holed out to long off after trying hard to prolong the innings in the company of tail-enders. De Villiers' 42 in two hours was the only score higher than Bavuma's.
Yadav drew first blood for India when he had left-handed opener Dean Elgar caught behind for 17, and later bowled a tentative JP Duminy on 1 in his second spell.
India resumed the day on 231-7, and Rahane and Ashwin saw off the second new ball and went about punishing the spin attack on a bright and sunny day in New Delhi.
Their partnership of 98 runs took India to 296-8, and helped set up a formidable total considering the previous highest innings in the series was 215 by India in the third test at Nagpur.
Rahane, 89 overnight, reached his century with a straight-driven four off pace bowler Kyle Abbott, and raising his arms in celebration.
He opened up from there, hitting offspinner Piedt for two sixes in an over, over mid-wicket and long-off. He was caught at short cover off legspinner Imran Tahir when he was stroking the ball beautifully. It was Rahane's first three-figure score at home, and fifth overall in 22 tests.
Ashwin, who produced some fine drives off the back foot early in the day, was lucky to escape a difficult chance while on 14. Amla took a low catch at first slip off Abbott, but replays showed the ball touched the ground. Amla himself was not sure the catch was clean.
Abbott eventually dismissed Ashwin for 56, and last-man Ishant Sharma in the space of three deliveries to finish with 5-40, and end India's innings after lunch.