Gavaskar said the move will allow skipper Virat Kohli to have an extra batsman in Ajinkya Rahane, while also securing a place for Rohit Sharma.
"Clearly, going into an overseas Test series with just five batsmen has not worked. Since South Africa are thinking in terms of going in with an all-pace attack, it might make sense for India to go in with Rahane and have Rahul keep wickets," said Gavaskar to a leading daily.
Ajinkya Rahane has not played in the first two Tests but could be recalled on the strength of a strong record in overseas Tests.
Dinesh Karthik was flown in as a replacement for injured wicketkeeper Wriddhiman Saha and could play at the expense of Parthiv Patel, who had a poor game with the gloves in the second Test at Centurion.
The Wanderers could live up to its reputation as a haven for fast bowlers, especially after South African captain Faf du Plessis expressed his disappointment with the slowness of the Centurion pitch where South Africa clinched the series last week.