More than 40000 folks strapped in for the last two hours of play at the Eden Gardens on Saturday. The game had zipped along faster than expected but the scene - with a dimming sun, shadows that would soon spill from the floodlights, and a couple of catchers around the bat, was set up for some late drama.

From the pavilion end, where the ball was at its most erratic, Kuldeep Yadav only got to finish his over that he'd begun before the Tea break. Rishabh Pant, the acting captain in Shubman Gill's injured absence, put both his left-arm finger spinners - Axar Patel and Ravindra Jadeja, to work. South Africa were only one down at this point, but the extremities of the conditions - the unreliable bounce off the surface, had reached a level where it was every batter for himself. There was no singular guide for survival as Jadeja and Axar got some shoulder workout in by firing rockets at over 95kmph. And some of those just kicked off or sneaked under from the very same length.

How do you really bat on such surfaces? Committing to the front foot brought edges and the forward short leg into play, and rocking back opened LBW avenues for the quick spinners. If South Africa were paying attention, this was exactly what Shubman Gill had flagged on the eve of the match - facing quicker spinners in India was never going to be the same as putting Pakistan's away at their home. Doing it on a pitch with such uneven bounce only added another stratum of difficulty.

In a hellish six-over phase shared by Axar and Jadeja, South Africa's batters took more mental bruises than they could count. Only Aiden Markram showed up in the wickets column during this stretch, but the batters at the other end were none the wiser about what might actually keep them in the middle. Markram fell while still unsure about committing on the front foot, so those who followed looked like they were mixing their plans on the fly.

Wiaan Mulder spent most of his 30 balls on the back foot and looked reasonably comfortable handling the pitch's misbehaviour. But the one good-length ball he leaned forward to, had his name on it. Tony de Zorzi went the other way and still paid the price. He committed forward to the first ball he faced, then rocked back, but the excess, unpredictable bounce did him in anyway - just as it did Mulder.

"To be honest with you, even we didn't expect the wicket to deteriorate so quickly," India's bowling coach Morne Morkel offered at the end of the day. "Looking at it the day before the game, even the morning of the game, I thought, when we watched the first couple of hours, that it was a good wicket. So it did deteriorate quite quickly, which was unexpected, but I think that's the beauty sometimes of playing in the subcontinent. You need to be able to adapt and you need to be able to react to conditions quite quickly."

Morkel knows all about the painful needs to adapt to such elements of a tour like this, having watched his teammates suffer far worse in 2015. Temba Bavuma was there too, and on Saturday, batted like only he knew to learn from the past.

But this Eden pitch isn't a raging turner, mind you, where every ball spun so much it pushed batters to the edge of existential crisis. This was a different kind of challenge, one where you couldn't always tell a regulation delivery from a demonic one. Bavuma took a blow to his head trying to sweep Jadeja, misread Kuldeep Yadav's googlies, but along the way still found a method that allowed him to stand his ground. He defended well and low, his lower centre of gravity working in his favour, at least on this evening.

Kyle Verreynne and Marco Jansen didn't trust the probability of that approach serving them, so they went out swinging. They were clinging to the basic template of trying to shift the pressure back onto the bowlers in a tricky situation like this, but it simply didn't work out. When the umpires decided they'd played enough for the day, Bavuma walked back with an unbeaten 29 off 78 and plenty more work ahead of him. South Africa were 93 for 7 in their second innings, but that was only half the tale of a chaotic second day.

What was meant to serve as a platform for India to breeze past South Africa's low first-innings total turned dramatic very quickly. India had finished Day 1 in a mood of circumspection, adding just nine runs off the last 10 overs, and somehow began Saturday with almost the same pulse. The ball wasn't darting around randomly yet as Washington Sundar tried to settle in and make the most of his new spot in the upper reaches of the batting order.

But Simon Harmer ensured that would be a project for another day, sending down a stirring spell with drift, turn and very little help from the pitch. Bavuma's proactive captaincy, Gill's neck spasm and a string of batting errors left India with only a 30-run first-innings lead. Morkel admitted it could, and should, have been 50 or 60 more. South Africa were then subjected to the vagaries from below.

"He who cries first, laughs last," Harmer said in jest, of the delicate situation at close of play. With South Africa sitting on a lead of 63 with three wickets in hand, there's still no definite direction for this game yet, even as the pitch deterioration is bound to continue in its linear, devastating fashion.

Hope and belief are sure to simmer in both camps, and that's perhaps the beauty of how this game is poised. Day 2 was defining, but there are more layers to this game waiting to be peeled away on Sunday.