At lunch, opener Dean Elgar (38 batting) was in company of AB de Villiers (19 batting), who is playing his 100th Test match, as the duo added 33 runs for the unbroken fourth wicket stand.
Elgar so far faced 79 balls and hit two fours and a six while De Villiers had two fours in his 27-ball unbeaten knock.
Ashwin (2/21) and Varun Aaron (1/28) shared the spoils in the first session which belonged to the home team despite Elgar's resolute fight and some classy shots by De Villiers after Virat Kohli opted to field.
Ashwin immediately got into the act with twin strikes in his very first over. It took him only two balls to draw the first blood for India. He flighted one that straightened after pitching and caught opener Stiaan van Zyl (10) plumb in-front. The ball was hitting the middle stump.
Faf du Plessis (0) wanted to use his feet as Ashwin altered the length but as he came down and tried to whip one, Cheteshwar Pujara at short-leg took a reflex catch crouching low as the visitors were reduced to 15 for two in eight overs. While third umpire adjudged it as clean catch, TV replays showed that part of the ball was touching the ground.