Australia 260 and 143 for 4 (Smith 59*, Ashwin 3-68) lead India 105 (Rahul 64, O'Keefe 6-35) by 298 runs
Scorecard and ball-by-ball details
It could have been worse for India, though it's hard to imagine how. Virat Kohli might have spontaneously combusted, or R Ashwin could have suffered a freak shaving accident in the morning and sliced his arm off. But aside from those admittedly long shots, the day went about as badly for India as it could have. By stumps, they were facing the very real prospect of losing a home Test to Australia for the first time since 2004.
Of course, the second day's play showed how quickly things can change, so India cannot be written off. But they will need to complete a chase of 300-plus to escape with a victory, something that has been achieved only once in Test history in India. On that occasion, back in December 2008, Sachin Tendulkar scored an unbeaten hundred to hunt down 387 against England in Chennai. But that was on a pitch that lacked the spite of this one.
This is a pitch on which 15 wickets tumbled on day two, including nine during a frenetic middle session, and on which India managed only 105 in their first innings. Steve O'Keefe ransacked the Indian middle and lower order for six wickets, which all came during a 25-ball spell after lunch. Three of those wickets came in one over, which triggered a stunning collapse during which India lost their last seven wickets for 11 runs, their worst such capitulation in Test history.
The collapse was not India's only problem, though it began ominously when KL Rahul, who scored nearly two-thirds of India's runs, suffered a painful injury to his left shoulder while slogging a catch into the deep. It was also a day on which Kohli was out for a duck for the first time in a home Test, and a day on which his Australian counterpart was given life after life. Steven Smith was dropped three times on his way to a half-century, and at stumps was still there.
The situation at the close of play was this: Australia were 143 for 4, leading by 298, with Smith on 59 and Mitchell Marsh on 21. Smith, in amongst his reprieves, used his feet well to India's spinners and never got bogged down. The only Australian who did was Shaun Marsh, sent in to open because a nauseous Matt Renshaw had been off the field too long during India's innings. Marsh spent 21 balls over a duck that ended when he was lbw to Ashwin's straight ball.
Australia had already lost David Warner in similar style for 10 in the first over, but if India hoped for an Australian collapse to follow their own they were disappointed. Peter Handscomb stuck around for 19 before he flicked a catch to leg gully off Ashwin, and in the unfamiliar position of No.5, Renshaw fought off sickness to strike 31 before holing out off Jayant Yadav. But the wicket India needed was Smith, and they had their opportunities.
On 23, Smith clipped Ashwin to leg-slip, much as Handscomb was to a few overs later, but M Vijay could not hold on to the first chance he got. Then on 29, Smith danced down the pitch and drove Ravindra Jadeja towards mid-on, where the substitute fieldsman Abhinav Mukund struggled to make ground to his right and dropped a hard one. At short-leg Mukund then put down a much more gettable chance off Ashwin when Smith had 37. Renshaw had also had a life on 25.
The contrast in fielding between the two sides could hardly have been starker. Handscomb in particular was responsible for two brilliant reflex catches, though the opportunities came because of the fine bowling of Australia's spinners - especially O'Keefe. He opened the bowling with Mitchell Starc but had failed to take a wicket in seven overs before lunch, yet after the break and a change of ends, he became unplayable.
Having had Rahul caught in the deep for 64, O'Keefe followed two balls later with the wicket of Ajinkya Rahane, whose edge was brilliantly taken at second slip by Handscomb, instinctively thrusting his right hand low to the ground. Another two balls later and Wriddhiman Saha failed to handle O'Keefe's turn and also edge, to be taken more conventionally but sharply nevertheless by Smith at first slip. India had gone from 94 for 3 to 95 for 6 in one over.
Nathan Lyon interrupted the procession of O'Keefe's wickets in the next over by having Ashwin caught at short-leg in extraordinary circumstances. Ashwin's defensive push went straight down and might easily have hit the turf, but instead struck him on the boot and bounced up temptingly for the close-in fielder, Handscomb. He dived forward and stuck out his right hand to complete a catch that showed both brilliant skill and alertness. India had lost four in eight balls.
O'Keefe claimed his fourth a few overs later when Jayant was dragged just out of his ground and Matthew Wade completed a crisp stumping, and India were 98 for 8. In his next over, O'Keefe achieved his maiden Test five-wicket haul when Jadeja danced down the pitch and slogged high to deep midwicket, where Starc took the catch.
The end came when Umesh Yadav edged O'Keefe to Smith at first slip, and India had fallen to their worst total in a completed home innings for nearly nine years. O'Keefe's accuracy and ability to turn some deliveries and not others, and some more than others, troubled the India batsmen in just the same way that India's own spinners had caused problems for Australia on the turning pitches in 2013.
The day had started with Australia on 256 for 9 and hoping that their last pair, Starc and Josh Hazlewood, might find a way to push the total up towards 300. Starc signalled his intent by slogging Ashwin for a boundary from the second ball of the day, but he did not survive until the end of the over. Fifth ball, Starc slog-swept to deep midwicket and was caught for 61, ending Australia's innings at 260.
Despite O'Keefe's later success, it was pace that brought Australia the first three wickets. Vijay was drawn into pushing outside off in Hazlewood's first over, and edged an inswinger behind for 10. Starc succeeded with a well-directed short ball that surprised Cheteshwar Pujara, who could do little but glove behind while trying to fend the ball away.
Two balls later Starc also had the prize wicket of Kohli for a second-ball duck. Perhaps trying to impose himself on the match as early in his innings as possible, Kohli drove expansively at a wide ball and edged to first slip. Two wickets in an over seemed like something special for Australia. If only they knew what was to come. By the end of the day, they were in prime position to end India's run of 20 home Tests without a loss.
Brydon Coverdale is an assistant editor at ESPNcricinfo. @brydoncoverdale