In his place, middle-order batsman Theunis de Bruyn is being announced as the concussion substitute. It's the third time in the history of the game when a concussion substitute will play the game. The other two are Jermaine Blackwood who replaced Darren Bravo in the third Test match against India this year, while Marnus Labuchagne was the first one to play as Steve Smith's substitute in Ashes.
Cricket rules for the World Test Championship were tweaked recently to allow players who suffer concussions during a match to be replaced in their team's Playing XI.
Earlier on Day 3, Elgar was hit by a nasty bouncer by Indian pacer Umesh Yadav on the helmet in the 10th over of second innings.
On this occasion, Umesh aimed a bouncer at Elgar but the left-handed batsman completely took the eye off the ball. It eventually rammed Elgar on his helmet, and the batsman immediately showed signs of discomfort.
Earlier, South Africa were enforced upon a follow-on after they were bundled on 162 in the first innings after India declared on 497/9. In the second innings, the Proteas' miseries continued as they are staring another big defeat in the Test series after losing half their side within 23 overs.