Centuries for Mathews and Chandimal but India still on top
Sri Lanka 356 for 9 (Chandimal 147*, Mathews 111, Ashwin 3-90) trail India 536 for 7 dec by 180 runs
Having kept it locked up all through this tour, Sri Lanka finally reminded everyone of the batting quality they possess, as centuries from Dinesh Chandimal and, at long last, Angelo Mathews helped them avoid the follow-on at the Feroz Shah Kotla.
Given how long they were kept on the field, India would probably not have enforced the follow-on anyway. The Chandimal-Mathews partnership alone consumed 79.1 overs.
And yet, once they found a way past that stand - having missed numerous opportunities to do so previously - India reasserted their dominance. R Ashwin, underbowled for most of the innings, led the way, taking three wickets on a pitch that only gave the spinners modest assistance, and the other three bowlers made valuable incisions too. Wriddhiman Saha, on a day when India's catchers kept letting down their bowlers, made three quality grabs behind the wicket.
Having got through the first session wicketless, and nearly doing so again in the second, Sri Lanka lost wickets in a clump, sliding from 317 for 5 and ending the day at 356 for 9, with Chandimal still at the crease on an outstanding unbeaten 147.
Right since his belated introduction on the second afternoon - he only came on in the 28th over - Ashwin had worried Mathews with his round-the-wicket angle, getting the ball to dip and land on an awkward length that made it difficult to deal with his natural variation. Some balls turned in, others carried on with the angle. The dismissal arrived courtesy the one that kept going across Mathews, who sent a thin edge through to Saha, who made a difficult chance look easy.
It was a moment of joy for Ashwin, and perhaps one of vindication too, for this was only his 19th over of the innings. Ravindra Jadeja, at that point, had bowled 34, Ishant Sharma 23, and Mohammed Shami 22. Perhaps the presence of two right-hand batsmen at the crease for such a long period had made Virat Kohli reluctant to turn to his offspinner, but again he had shown his ability to threaten both edges of the bat.
As always, Ashwin began finding more bite after getting a few overs under his belt and working out what pace to bowl at, with what trajectory. On this Kotla pitch, he began delivering his offbreaks with far more overspin than sidespin. This overspin, which led to dip and bounce, sent Roshen Silva on his way for a duck on debut, caught bat-pad. Two wickets, two right-handers. The next one was a left-hander, Niroshan Dickwella, who lost his off stump while trying to cut Ashwin's round-the-wicket arm ball.
Chandimal added a brisk 61 with Sadeera Samarawickrama, who came out at No. 6, having been off the field since being hit on the helmet at short leg on day one. Having hit seven fours in an attractive 33, however, Samarawickrama edged Ishant while chasing at a widish ball, and Saha dived to his right to take a spectacular low one-hander. A little later, another dive to his right sent back Suranga Lakmal, who edged an away-seamer from Shami.
Jadeja grabbed the ninth wicket, typically an lbw as the batsman, Lahiru Gamage, propped forward and played for non-existent turn.
Given how quickly the lower middle order disintegrated, India may have wondered what the match situation might have been had they held on to all their chances.
In all, they let Mathews off three times. Virat Kohli had shelled him on 6 on the second day, at second slip, and Rohit Sharma repeated the trick when he was on 98: at the same position, off the same bowler, Ishant, when Mathews made a similar mistake, poking away from his body without moving his feet. This was a straightforward chance, at chest height, when India had just taken the second new ball.
Then, on 104, Mathews looked to hit Jadeja over mid-off, but didn't get the elevation he desired. Vijay Shankar, substituting for M Vijay, timed his jump well and got his fingers to the ball at full stretch, but failed to hold on.
It was that kind of innings for Mathews, an innings defined by struggle. In the first hour, he was beaten more than once by Shami, who bowled a spell of testing line, the odd bouncer, and just a touch of seam movement, all at high pace. Camped on the back foot against Ishant Sharma, he reached out for full balls and skewed and sliced them squarer than intended.
As the session wore on, Ishant packed the leg side and peppered him with short balls. Perhaps he overdid it, but there were still a few awkward moments, such as a pull that flashed narrowly wide of the man at short fine leg.
But Mathews grew in assurance thereafter, utilising all his know-how to keep India's bowlers out, but it was seldom pretty. He was quick to punish anything on his legs, and targeted Ashwin for his rare flashes of adventure, such as a delicate lap-sweep to go from 83 to 87. Otherwise, it was sheer, stubborn resistance.
Like Mathews, Chandimal was troubled by Shami early on. A short ball from wide of the crease smacked him on the glove, and three balls later he was a little slow getting on the front foot to a full ball in the channel, the resultant edge falling short of first slip. At one point, the smoggy atmosphere caused him some difficulty too, bringing the physio onto the field. Otherwise, he looked composed as he settled into the kind of defensive innings he has now become adept at playing - think SSC, 2016, or Abu Dhabi, a couple of months ago.
Occasionally, he unfurled an eye-catching attacking shot - such as a cover drive off Shami or a twinkle-toed whip against the turn off Jadeja - but otherwise it was all vigilant defence as he moved to his third successive half-century of the series, looking increasingly secure.
After lunch, he picked up his scoring too, as the bowlers' workloads began occasionally to tell on their accuracy. Ishant dropped short a couple of times, and Chandimal put him away to the point and fine leg boundaries, but the shot of his innings, Sri Lanka's innings, and perhaps even the match, came off Shami. It wasn't a bad ball, banged in close to off stump, extracting a good amount of bounce, but Chandimal, feet off the ground, got off his feet and punched it to the cover boundary.
Karthik Krishnaswamy is a senior sub-editor at ESPNcricinfo