Ravindra Jadeja (L) watches batting partner Rohit Sharma celebrate scoring a double century during the last Test match in Ranchi on Sunday. AP
Sharma made 212 as India declared their innings on 497 for nine on a weather-interrupted day two in Ranchi.
The in-form Sharma, who hit twin centuries on his debut as Test opener at the start of the series, was involved in a crucial 267-run fourth-wicket stand with Ajinkya Rahane, who made 115.
The hosts slipped to 39 for three on day one after an inspirational spell of fast bowling by Kagiso Rabada, who claimed two early wickets before Sharma took charge.
"I (have) played only 30 Tests," said Sharma. "In terms of what was thrown at me, I would definitely say it was probably the most challenging one."
"Having played only three Tests as an opener, I know I have a long way to go. Of course I will take a lot of positives but I'm not reading too much into it," he added.
The tourists were in trouble at nine for two, with Indian fast bowlers sending the opposition openers back to the pavilion.
Zubayr Hamza, on nought, and skipper Faf du Plessis, on one, were at the crease when bad light stopped play for the second successive day.
Mohammed Shami got the left-handed Dean Elgar caught behind for nought and fellow paceman Umesh Yadav sent Quinton de Kock trudging back to the pavilion for four.
Sharma praises Rahane
The day belonged to Sharma who moved from 199 at lunch to 200 with a six off paceman Lungi Ngidi in the third over of the afternoon session as the raucous home crowd stood up and applauded.
The in-form opener hit another six off Ngidi before falling to Rabada and returned to the pavilion with handshakes from the South African side.
The senior batsman surpassed his previous best of 177 on his debut against the West Indies in 2013.
Sharma, who has three double centuries in his already illustrious one-day career, smashed the ball all around the park as he hit 28 fours and six sixes in his 255-ball stay.
But Sharma credited vice-captain Rahane, who recorded his 11th Test hundred, for his team's rescue act that started with the batting duo's marathon stand.
"We have seen him for a long time. The way he has taken forward his Test career. He has always rescued the team from difficult circumstances," said Sharma.
"He has not done this in just one or two innings, but he's been doing it consistently. It shows how strong mentally he is and the hunger for runs. We have seen this not only in India and outside."
Rahane, who started Sunday on 83, became debutant spinner George Linde's first Test victim.
Linde got good turn with his left-arm spin in an extended afternoon session as he claimed Ravindra Jadeja for 51.
He returned figures of 4-133 and said his team will fightback despite their bad start.
"Obviously was a bad start. It's not the way we wanted it to go but tomorrow is another day," he said with a smile.
"We were positive. Guys were smiling in the dressing room, so we are ready for tomorrow. We are not going to sit back and relax, we will try to take the challenge on."
India is aiming for a whitewash after taking an unassailable 2-0 lead in the three-match series.
Rohit Sharma is unbeaten on 117 after scoring his third hundred in this series. He has shared 185 runs for the unbroken fourth wicket with Ajinkya Rahane, who is 83 not out.
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