New Zealand 431 (Guptill 156, Williamson 88, McCullum 75, Pradeep 4-112) and 171 for 1 (Latham 72*) lead Sri Lanka 294 (Karunaratne 84, Chandimal 83) by 308 runs
Scorecard and ball-by-ball details
In stark contrast to the previous two days in Dunedin, the third was overcast, cold and windy - conditions that were as familiar to New Zealand as they were foreign to Sri Lanka. The visitors struggled to cope: their batsmen succumbed to the moving ball, their bowlers toiled in the strong breeze, and their fielders put down catches in the chilly weather. The upshot was an ever-widening distance between the two teams, exemplified by New Zealand's 308-run lead with nine wickets in hand and two days remaining.
Sri Lanka's troubles began in the first over, when Tim Southee dismissed Dinesh Chandimal with his second ball. The delivery swerved into the right-hander from over the wicket, landed on a good length around middle and off stump, and seamed away. Chandimal was squared up in his crease as he tried to defend, and Martin Guptill dived across first slip from second to catch the edge.
In his second over, Southee swung two consecutive balls on to Kithuruwan Vithanage's pads and the batsman glanced both to the fine-leg boundary. The next delivery slanted away from the left-hander with a scrambled seam, and Vithanage chased it with a cover drive, giving BJ Watling his fifth catch. Sri Lanka had lost both overnight batsmen in the first 15 minutes.
From 209 for 6, Sri Lanka were lifted briefly by a plucky stand of 43. Milinda Siriwardana, playing in only his third Test, attacked the fast bowlers - driving through cover and down the ground, pulling and cutting too. Herath batted cautiously after successfully reviewing a catch down the leg side that had gone off his boot, and took 22 balls to get off the mark.
With around 30 minutes to lunch, New Zealand began bowling short, aiming at the batsman's ribs with catchers on the leg side. Herath was the primary target, and was hit on the gloves by Wagner and on the helmet by Southee. When New Zealand came at Siriwardana with short balls, he pulled. He was caught on the long-leg boundary by Doug Bracewell, who fell over the rope because he had been back-pedalling and could not control his momentum. But three balls later, Wagner sent down another short delivery and Siriwardana fended it to Ross Taylor at slip.
Brendon McCullum continued the short-ball attack after lunch, often placing no fielders in front of the wicket on the offside. Wagner began the 100th over with a bouncer, Herath ducked. The second ball was also short, Herath was beaten on the pull. The third was short too, and Herath top-edged towards long leg, where Trent Boult ran in at speed to take the catch. He had made 15 off 74 balls, and was the only batsman to not be caught by the wicketkeeper or the slip cordon.
Sri Lanka were eventually dismissed for 294 in 117.1 overs - a commendable period of time for such a raw batting line-up - having added 97 for 6 on the third day, conceding a first-innings lead of 137.
Like they had done while batting, Sri Lanka sought to take time out of the Test in the field too, by slowing New Zealand down with more accurate bowling and defensive fields - Angelo Mathews had men out at deep point and square leg early on. It worked for the hour before tea, when Guptill and Tom Latham minimised risk against the new ball.
They lifted the tempo in the final session, though, with Guptill taking charge. He could have been caught on 19 and 42, but Kusal Mendis put down a fierce cut at cover, and Suranga Lakmal failed to catch a drive on his follow-through. It was the first time New Zealand had two half-century opening partnerships in a Test since December 2009.
New Zealand targeted Herath once again, Guptill charging down the pitch to hit powerfully to and over the long-on boundary in the same over. He looked good for a second 50-plus score in the Test until he was bowled by a delivery that shot through at ankle height, an aberration on this surface. It was scant consolation for Herath, who conceded 39 runs in eight overs.
Williamson and Lathan built on the opening stand of 79, by raising their half-century stand in 61 balls, rapidly building the lead. Williamson passed 1000 runs at an average of more than 90 for the year by stepping out and lofting Herath to the wide long-on boundary, while Latham finally looked to be shaking his tendency to give away a start.
He ended the day unbeaten on 72, Williamson on 48, their partnership of 92 coming at 4.27 an over. New Zealand will aim to continue at similar pace on the fourth morning, to give themselves five sessions to dismiss Sri Lanka to take a lead in the series.
George Binoy is an assistant editor at ESPNcricinfo