A typically brutal century from Virender Sehwag helped India tighten their grip on the second day of the second Test against South Africa at Eden Gardens.
Sehwag smashed a belligerent, unbeaten 125, consolidating India's position with a fruitful association with Sachin Tendulkar (65 not out) as India put South Africa's attack to the sword in an entertaining afternoon session.
The visitors were bowled out for 296 in the morning and India had whittled the lead down to 64, reaching 232 for two, at the tea break.
South Africa were bowled out inside four overs in the morning, Zaheer Khan adding the final wicket of Wayne Parnell (12) to his kitty and helping him finish with four for 90 from 22 overs.
Sehwag and opening partner Gautam Gambhir (25) began India's reply with a barrage of boundaries against the new ball, raising 73 for the first wicket in quick time.
Sehwag began his innings with a single gleaned from an inside edge onto the pad off Morkel and then cut loose with a flurry of boundaries.
He lashed Dale Steyn for three consecutive hits to the fence in the bowler's second over, smacked three more from Morne Morkel's third over and blasted Parnell for a four and a six in the bowler's first over.
He was briefly in contention for the fastest half-century in Test cricket, but the dismissal of Gambhir halted the barrage of runs.
Gambhir, who had made a total of 13 in two innings at Nagpur, also seemed to have the measure of the Proteas pacemen, but was run out after a mix-up with his partner.
Sehwag had inside-edged a drive to deep square leg and had turned for another run when he changed his mind.
Gambhir had already responded and was stranded half way down pitch when the throw from Alviro Petersen came in from the deep.
South Africa then had the door ajar when Murali Vijay (seven) was caught smartly by stand-in wicketkeeper AB de Villiers off Morkel and they could have taken control had Jean-Paul Duminy not grassed Sehwag on 47 at slip off Morkel.
The opener went on to reach his half-century - off 41 deliveries - and only went from strength to strength.
The afternoon session began in another blaze of boundaries as Tendulkar, after a relatively slow start, hit his stride.
Thereafter there was little respite for South Africa as both batsmen took heavy toll, Sehwag raising his 19th Test century off only 87 deliveries with his 16th boundary - off Parnell.
Tendulkar raised his 55th Test half-century shortly later, the duo extending their fourth-wicket association to 150 at the interval.