Dean Elgar hit a boundary-studded century as South Africa scored rapidly on the second day of the first Test against India at SuperSport Park in Centurion on Wednesday.
Elgar made 115 not out in a South African total of 194 for three at tea after India were bowled out for 245.
KL Rahul scored 101 for India – his eighth Test century and his second in successive matches in Centurion.
South Africa added 145 runs for the loss of two wickets in 33 overs in an afternoon session extended to make up for overs lost in a rain-hit first day.
Elgar, 36, who has announced he will retire from international cricket after the second Test in Cape Town next week, had to survive a challenging start against Indian new ball bowlers Jasprit Bumrah and Mohammed Siraj.
But the left-handed opening batsman blossomed with some of the most fluent stroke play of his career when India surprisingly did not use the two strike bowlers immediately after lunch.
Elgar reached his fifty off 79 balls with ten fours and his 14th Test century was made off 140 deliveries with nine more boundaries.
Elgar and Tony de Zorzi (28) put on 93 for the second wicket and new cap David Bedingham looked composed in making 32 not out in an unbeaten fourth wicket stand of 81.
Rahul earlier was mainly responsible for India adding 37 runs to their overnight total of 208 for eight after rain delayed the start of play by 25 minutes.
Rahul was last man out after a 137-ball innings which included 14 fours and four sixes.
Brief scores at tea:
India 245 in 67.4 overs (V. Kohli 38, S. Iyer 31, K. Rahul 101; K. Rabada 5-59, N. Burger 3-50).
South Africa 194-3 in 49 overs (D. Elgar 115 not out, D. Bedingham 32 not out; J. Bumrah 2-35).
Match situation: South Africa trail by 51 runs with seven wickets remaining in the first innings.
Toss: South Africa