The pluck was evident in Virat Kohli's bat on day one, and on Thursday it rubbed off to the bowlers who turned the Wanderers Test into anybody's game.
India took a bold decision to bat first in a country where they have never won a Test series, and 255 for 5 was a good return for any subcontinent team in the first 90 overs of a series in the Rainbow Nation.
But it was undone by South African fast bowlers, who came back on Thursday morning with their radars adjusted to mop India up for 280. An extra-cautious India could add just 25 runs to their overnight score. And just when it looked Graeme Smith and Hashim Amla had nailed their tents in the middle of the Wanderers, Indian pacers ran amok.
At 130 for 1, having added 93 for the second wicket, Smith and Amla looked inseparable but unaware that the ball was now old enough to reverse-swing and turn the match on its head.
The scoreboard stood frozen at 130 as Amla, Jacques Kallis and Smith walked past it into the dressing room - watching the wickets column turn from 2 to 3 to 4.
Amla trusted the bounce a bit too much. A ball that he thought would go safely over the stumps seamed in to hit the top of his off-stump. Next ball, the 38-year-old Kallis wasn't warmed-up enough to get his feet moving and fell lbw for a first-ball duck.
Zaheer had been probing Smith since the start of SA innings and even saw Ashwin dropping him in the slips. But that didn't put Zaheer off, and once it started reversing, he nicely set up the South African skipper. Having bowled a few innocuous ones outside the off-stump, Zaheer swung the 39.2-over-old ball sharply back in to catch Smith in front for 68.
By now, it was pretty evident that the Indian players had taken good care of the ball to get it reversing for Zaheer & Co. Watching that, Dhoni brought his fastest bowler, Mohammad Shami, back into the attack; and the Indian skipper's Midas touch worked again.
Shami removed JP Duminy and De Villiers in the first three balls of his comeback spell. Duminy was forced to play at a ball that was angled across him and found the edge through to the slip cordon. De Villiers looked good but not on the 21st ball he faced that thudded into his pads in front of the stumps. South Africa, at 146 for 6, had lost five wickets for 16 runs. India were right on top.
But South Africa managed to retaliate with a rearguard action from Faf Du Plessis and Vernon Philander who took the South African score into safer territory on the other side of 200, reducing the gap with India's 280 to just 67.
Nonetheless, the half-an-hour demolition job after tea on Thursday said a lot about the character of this Indian bowling attack that pushed South Africa back to the wall and has given India a chance to win the Wanderers battle.