India pacer Shardul Thakur grabbed his maiden five-wicket haul as South Africa lost the momentum towards the end of the afternoon session to reach 191 for 7 at tea on day two of the second Test.
Thakur (13.1-3-43-5) with his happy knack of breaking partnerships more than compensated for Mohammed Siraj's hamstring injury as Keegan Petersen (62 off 118 balls) and the in-form Temba Bavuma (51 off 60 balls) laid the platform only to fritter away a promising start.
The only silver lining for Proteas is that they are now only 11 runs short of India's first innings total of 202.
In fact, just like skipper Dean Elgar (28 off 120 balls) and Petersen had a 74-run stand broken in the first session, Bavuma and keeper Kyle Verreynne (21) had added 58 runs in a fifth wicket stand before Thakur once again got into the act.
If outswingers worked well in the first session, it was the scrambled seam off-cutters that did the trick in the post-lunch dismissals.
In case of Verreynne, the ball cut back from 'fifth' off-stump to beat his bat while Bavuma just like first Test, lost his concentration trying to whip one that was drifting down but had enough bounce to take his gloves and Rishabh Pant completed a fine leg-side catch.
Pant had three catches and one of which off Rassie van der Dussen looked like having hit the ground before he picked up.
While South Africa might still get ahead but to be where they are after being 88 for 1 in the first 90 minutes of the second certainly means a lost opportunity on a track where it's difficult to feel set.
Earlier, Shardul Thakur's knack of picking crucial wickets came in handy as his triple strike brought India back in the game, leaving South Africa at a jittery 102 for 4 going into lunch on day two of the second Test.
Thakur (3/8 in 4.5 overs), the fourth seamer in the side, raised his game to remove the stodgy Dean Elgar (28 off 120 balls) and young Keegan Petersen (62 off 118 balls), who looked good en route his maiden half-century in Test cricket.
Then at the stroke of lunch he dismissed Rassie van Der Dussen (1 off 17 balls) to a doubtful catch from wicketkeeper Rishabh Pant which seemed to have been grassed.
From 88 for 1, South Africa lost three wickets for 14 runs in the last half hour to just throw away the advantage.
Although Jasprit Bumrah (0/34 in 17 overs) and Mohammed Shami (2/52 in 20 overs) bowled their hearts out without getting desired results, Thakur's strikes at the fag end of the session was a big boost for KL Rahul's men.
Skipper Elgar, who looked to defend stoically at one end, had Thakur getting one to move away which took the outside edge of South African skipper's bat into Pant's gloves.
In case of Petersen, it was a rank bad shot as the seamer got a hint of outswing but the delivery was pitched slightly short of drivable length and the half-hearted push only resulted in Mayank Agarwal taking a smart catch in second slip.
Young Petersen, whose highest Test score till Tuesday was 19, looked in good touch having struck nine boundaries including a glorious cover drive off Shami.
Along with Elgar, he added 74 for the second wicket and a stand like this would have kept the hosts in good stead before Thakur came from nowhere to turn the match on its head.
With inputs from PTI