New Zealand 178 and 231 for 2 (Latham 74*, Taylor 25*) lead Sri Lanka 104 (Mathews 33, Boult 6-30, Southee 3-33) by 305 runs
Trent Boult claimed six wickets in 15 balls of searing late swing to turn the second Test dramatically in New Zealand's favour. At stumps, the hosts had piled on 231 for 2, stretching their lead to a commanding 305, with three days left to play.
Having begun 100 runs adrift and with six wickets still in hand, Sri Lanka's day two was disastrous - their lower order clueless against Boult's sublime bowling in the morning, and their seamers toothless in the afternoon and evening sessions.
In addition to the heroics of Boult, who set a record in requiring only 11 balls to take five wickets, the hosts also had the benefit of a half centuries from openers Jeet Raval and Tom Latham, who put on 121, before Kane Williamson also contributed a smooth 48. Dilruwan Perera became the first bowler to pick up 50 Test wickets in 2018, but so bleak is Sri Lanka's outlook in this game, this may feel like a hollow achievement.
Boult, who had been outstanding from the outset on day two, regularly threatening to swing a ball between right-hander Roshen Silva's bat and pad. He first broke through in his third over, having Roshen caught at second slip attempting a loose drive. That wicket brought to end Sri Lanka's best partnership - Roshen's 43-run stand with Mathews.
In his next over, Boult's swing, which went from right to left (in to the right-hander, away from the lefties) was irresistible. Niroshan Dickwella drove at a ball that curved deviously away from him at the last moment, with Tim Southee diving across from third slip to complete a spectacular one-handed catch.
The remaining dismissals were all lbws - each of them plumb. Dilruwan, Suranga Lakmal, Dushmantha Chameera and Lahiru Kumara all either left or missed deliveries they had been convinced were heading down the leg side, only for each of those balls to change course fast and late, striking them in front of middle stump. The only confident stroke right through that 11-ball passage, during which five wickets fell, was Chameera's blocking out of a hat-trick ball, after Dilruwan and Lakmal had fallen to consecutive deliveries to end the previous over.
Where other quicks had found movement off the pitch through day one, Boult was the first bowler in this match to generate vicious movement in the air. Sri Lanka will perhaps feel their tailenders could have done better to get some bat in the way of the deliveries that dismissed them, but the batsmen higher up had also been guilty of being drawn into too many loose drives, which had exposed the lower order to Boult while conditions were still supremely suited to his bowling.
Batting conditions did ease when the sun broke through the clouds to dry out the pitch slightly later in the day, but with Boult having sent New Zealand soaring to a 74-run first innings lead, their openers cautiously played out a vital seventeen overs before lunch, to see the back of the really difficult batting conditions of the day.
Not only did they avoid the mistakes that had led to Sri Lanka's downfall, being careful not to drive loosely in particular, they also left judiciously and were content to merely push at even the overpitched balls, rather than hitting out. Latham and Raval were so watchful before lunch that it was not until the eighth over that the first boundary of the session was struck - Raval flicking an overpitched Kumara delivery past midwicket for four. That was also the only boundary until the 15th over.
After lunch, the New Zealand innings steadily gained momentum, the batsman having eased into a run-scoring rhythm. Raval and Latham still played and missed repeatedly, but having survived the good balls, increasingly made sure to punish the bad ones. Latham was strongest down the ground, hitting three of his first four fours in the arc between long off and wide long-on.
Raval, who was the more positive batsman, scored heavily square of the wicket. In fact, 44 of his runs - 59% of his eventual 74 - came behind square. As Sri Lanka's frustrated quicks began bowling more and more short-pitched deliveries, Raval and Latham generally rode the bounce with confidence.
The only exception came when Latham mis-hit a hook off Suranga Lakmal on 32, only for the tough chance to be dropped by a diving Dushmantha Chameera on the fine leg boundary.
Raval progressed to his first half-century in over a year, completing the milestone via a thick edge through gully. He and Latham batted out the afternoon session without losing a wicket, before Raval was eventually dismissed after tea, caught bat-pad to give Perera his 50th wicket of the year. Williamson then produced another of his effortless innings, scoring heavily square of the wicket and through third man, with the ball now having completely lost its newness and with the Sri Lanka attack having gone flat. He was out uncharacteristically - trying to push at a back-of-a-length Lahiru Kumara ball that was passing too close to his body, winding up only sending an edge to wide slip.
Ross Taylor made 25 not out off 27 balls in the final overs of the day, taking particular pleasure in clattering short, wide balls through point. Latham was 74 not out off 213 balls at the close.