South Africa slide from 88 for 1 to 102 for 4 to go to lunch on the second day 100 runs behind
Lunch South Africa 102 for 4 (Petersen 62, Bavuma 0*, Thakur 3-8) trail India 202 by 100 runs
That meant South Africa went into the break at 102 for 4 after being 88 for 1 at one stage.
Both came close to picking up wickets.
Bumrah got one to come back into Petersen after a string of awayswingers. The batter shouldered arms and, luckily for him, the ball went over the stumps.
A few overs later, Elgar edged one off Bumrah and Pant took it low; the on-field umpires referred it upstairs with the soft signal as out. The third umpire, though, concluded that it was a bump ball.
In the next over, Shami cut Petersen in half but on this occasion, too, the ball sailed over the wickets.
Petersen, who is playing his fourth Test but was facing spin of any kind for the first time, too cut Ashwin to the cover boundary.
Eventually, it was Thakur who broke the stand when Elgar edged to Pant for 28. Petersen reached his half-century with a boundary off Shami and celebrated it with two more fours in the over, but his rare loose shot outside off against Thakur gave India the chance to make a comeback.
Hemant Brar is a sub-editor at ESPNcricinfo