Cape Town - Morne Morkel picked up two quick wickets in India's second innings early on the third day in Delhi.
India began the day with a lead of 213, but were rocked when Morkel struck to remove Murali Vijay and Rohit Sharma in succession, leaving the tall speedster on a hat-trick and India reeling at 8/2.
Cheteshwar Pujara managed to fend off the hat-trick delivery.
The Proteas still have a mountain to climb after they were rolled over for 121 in their first innings and will have to dismiss India very cheaply to have any hope of winning the final test in the series.
India lead the series 2-0.