An unbeaten double century from Hashim Amla helped South Africa to compile 558-6 declared after two days of the first Test against India at Nagpur.
Resuming on 115 with his team on 291-2, Amla took his record stand with Jacques Kallis to 340 before Kallis fell for 173, spanning close to seven hours.
Amla was dropped twice on 149 but made 253, his maiden double century, defying the bowlers for almost 11 hours.
South Africa can reclaim to spot in the rankings with victory in this two-Test series, with India needing a draw to retain their number one position.
Kallis took until the ninth over of the morning to add to his overnight 159, and made just 14 in almost 90 minutes before an inside edge on to the pad was snaffled by Murali Vijay at short-leg to end the highest South African third-wicket partnership against India.
Amla's first reprieve came when Murali put down a straightforward chance at short-leg and next ball wicketkeeper
Mahendra Singh Dhoni put down a difficult opportunity.
But Natal-born Amla, whose grandparents migrated from India, overcame the tricky spell and reached his double hundred with a delightful drive off spinner
Virender Sehwag.
AB De Villiers added quick runs with clever use of the feet against the spinners to notch his 21st Test fifty.
After he skewed one and JP Duminy was lbw cheaply having missed a sweep, the redoubtable Mark Boucher shared 78 with Amla before mis-timing to cover which brought about the declaration.
India started positively in reply, however, and Gambhir hit Morne Morkel for boundaries in successive overs, while Sehwag whipped Dale Steyn through midwicket for his first four.
"A double century is always special, be it any opposition," said 26-year-old Amla.
"But obviously it feels great that it came on Indian soil. My game plan was to stay at the wicket for as long as possible and put the team in a strong position."
Former South Africa batsman Gary Kirsten, the India coach, paid tribute to his countrymen after the barrage of runs.
"Our bowlers bowled their hearts out," he said. "You have days when you do not really get the results that you want, but from my point of view, I am very happy with the effort that we put in.
"If the batting from the other side is really good, then you must acknowledge that. Amla played a superb innings. Both Kallis and he batted exceptionally well.
"Full credit to them, they did a fantastic job considering they came in to bat when they were two down for six."
