After being dismissed for just 201 by the disciplined South African bowling attack, India struck two vital blows during the first day of the first Test in Mohali on Thursday.
Ashwin accounted for van Zyl (5) and Ravindra Jadeja for the dangerous Faf du Plessis (0).
At the end of the day's play, South Africa were 28 for 2 with skipper Hashim Amla (9) and Dean Elgar (13) are at the crease.
With the pitch turning, Indians has to capitalise on the good start given by their spin bowlers.
All in all, 12 wickets has fallen during the day for 229 runs.
Earlier, the India batsmen failed to capitalise on a good toss won by Virat Kohli during the first day of the first Test in Mohali on Thursday.
The South African bowlers tightened the screws and dismissed India for 201 with Dean Elgar, the part-timer taking four wickets. Vernor Philander and Imran Tahir took two wickets apiece.
India were staring down the barrel after being reduced to 168 for seven at tea.
Murali Vijay (75) scored a defiant fifty before falling to Simon Harmer, as the visitors dominated the first two sessions at the IS Bindra Stadium.
Elgar turned out to be the unlikely hero after India skipper Virat Kohli opted to bat.
Ravindra Jadeja (26 batting) and Ravichandran Ashwin (4 batting) are fighting on to try and give some respectability to the Indian total.
Starting the post-lunch session on 82 for three, India saw some resistance from Vijay and Ajinkya Rahane (15), but the reintroduction of left-arm spinner Elgar into the attack again proved worthwhile for the visitors.
India lost two wickets in quick succession between overs 38 and 40. Rahane was the first to go following an expansive drive off a looping delivery that pitched outside the off-stump, the edge flying to first slip.
Elgar struck again on the very first delivery of his next over, sending back wicketkeeper-batsman Wriddhiman Saha to be on a hat-trick.
All-rounder Jadeja played out the hat-trick ball but India’s struggle was far from over.
Vijay got to his fifty with a thickish edge that flew past the lone slip, for his 12th Test half-century. Vijay, who had stitched a 37-run fourth wicket partnership with Rahane, managed a 38-run partnership with Jadeja to raise hopes of an Indian recovery.
But that was not to be as off-spinner Simon Harmer got the dangerman trapped LBW and the hosts slipped further. Amit Mishra (6) also couldn’t resist the temptation against Elgar’s looping deliveries and fell while attempting to hit past mid-on.
Ashwin survived a scare after he was trapped LBW off debutant pacer Kagiso Rabada as it turned out to be an over-stepped no ball.
Earlier, electing to bat in overcast conditions on a slow and low IS Bindra stadium pitch, India lost Shikhar Dhawan without a run on board, but Vijay and Cheteshwar Pujara (31) steadied the boat with a 63-run stand before the bowlers strike back.
Vernon Philander drew the first blood with a moving delivery which Dhawan slashed, managed an edge, and the ball flew into the waiting hands of skipper Hashim Amla at first slip.
Dhawan though would have been disappointed with his failure on a ground where he scored his debut hundred in 2013 — a breezy 187 against Australia.
Pace spearhead Dale Steyn kept up the pressure from other end as the batsmen found it hard to score freely.
But the drama unfolded after the drinks break when India saw two quick wickets fall in the space of four deliveries to give away the advantage to the visitors.
The introduction of Elgar proved to be an intelligent move as he trapped Pujara.
Test skipper and birthday boy Virat Kohli (1) then walked out to the center amidst loud cheers from the sparse crowd gathered at the stadium, but his stay lasted just four balls.
Rabada got the prized wicket of Kohli, his first Test scalp, after the star batsman tried to check his shot off a length delivery and the leading edge went to Elgar, who completed a good low diving catch at cover.
The delight in the opposition camp was palpable as Amla kept on rotating the bowlers in his effort to make more inroads.
