Sri Lanka 356 and 45 for 1 (Silva 20*, Craig 1-0) need another 345 runs to beat New Zealand 221 and 524 for 5 dec (Williamson 242*, Watling 142*)
Scorecard and ball-by-ball details
Kane Williamson and BJ Watling used the slow grind to drive away the thoughts Sri Lanka had at the start of day four of winning the Wellington Test and levelling the series. In the process, they first broke the 27-year-old record of New Zealand's highest sixth-wicket partnership against Sri Lanka, and then smashed the all-time record for the sixth-wicket stand set up last year by Watling and Brendon McCullum at the same ground, making redundant the bronze plaque ground authorities had set in concrete only three days ago.
During the course of their unbeaten 365-run partnership, Williamson reached his maiden Test double-century, while Watling grafted his way to his fourth Test hundred. The two batsmen stretched Sri Lanka's wait for a wicket to almost eight hours, before McCullum provided the visiting fielders some relief by declaring an hour before the close of play. The 390-run target was well past the highest total successfully chased at the ground.
Even though the pitch was flat, Sri Lanka were left with the tricky task of surviving 17 overs on the fourth evening. Trent Boult and Tim Southee did not manage any extravagant swing but still beat the Sri Lankan openers regularly. Mark Craig struck in his first over, getting Dimuth Karunaratne caught at mid-off. It was the only wicket to fall on the day.
Williamson's fighting innings did his growing reputation as one of the world's best batsmen no harm. He has been in terrific form in all forms of the game and his previous two Test centuries had both been in excess of 150. He was dismissed a couple of hits short of a double-century just over a month ago, in Sharjah, but there was the same inevitability about him getting to the landmark in Wellington, as there was with Kumar Sangakkara, once he had manoeuvred the New Zealand innings safely till lunch.
Plenty of singles were collected square of the pitch on both sides. His drives were controlled shots, yielding twos or three. The first boundary came in the 13th over of the morning - also, the first for 30 overs - as Williamson stepped out to drive Herath to wide long-on, moving to 99 with that shot. An over later, he clipped one to the leg side to complete his ninth century - and his third in the second innings. His second boundary of the day, one with more flourish, came late in the first session as he punched Nuwan Pradeep through covers.
After lunch, however, Williamson's intent signalled New Zealand had a target in mind for Sri Lanka. The boundaries were not easy to get with the field scattered, but he kept pushing the ball in the gaps with efficient, but hardly noticeable, shots. He stepped out against Rangana Herath, who had been ineffective in this Test, and chipped over midwicket to reach the 200 landmark, the shot also bringing the 300 of the partnership between Williamson and Watling. Two overs later, he played the perfect cover drive off the second new ball to become the fastest New Zealand batsman to 3000 runs, beating Martin Crowe's record by three innings.
Sri Lanka did not help their chances by letting slip another opportunity to dismiss Williamson early in the day. The batsman had been dropped on 29 and 60 on the third day, and soon after he reached his hundred Herath extracted the outside edge with a delivery that reared sharply off an otherwise benign pitch, but the wicketkeeper Prasanna Jayawardene could not hold on to the deflection.
It was a tough chance, and the only one the bowlers were able to generate all morning. By the time a second came - a missed stumping with Williamson on 233 - Sri Lanka were far behind in the game. There was hardly any swing, seam or spin from the pitch. Sri Lanka's bowlers tried different lines, bowled from either sides of the stumps, the captain set up leg-side traps, and managed to keep the boundary count to three in the first session, but Williamson and Watling kept turning the strike over.
With the batsmen hardly facing any trouble and plenty of time remaining in the match, the match drifted into the zone in which the probability of a Sri Lanka win rapidly diminished towards zero. Slips were removed and men placed in the deep to keep a tab on the scoring. But that in turn opened up gaps for Williamson and Watling to pick more singles and twos.
Watling's batting heavily depends on dabs behind point and clips through square leg. It's his comfort zone and he had no intentions of coming out of it. It meant that while Williamson was immovable at the other end, Watling also was testing the bowlers' mental resolve, blocking everything out. It was fitting that Watling's century came off a soft push to cover point, off the 270th delivery he had faced.
For most of the day, he had just one boundary to his name. Even after crossing his century, his primary mode of making runs was ... running. Only towards the end of the innings did he played forceful shots in front of square, including a lofted shot off Herath that landed over the boundary at wide long-on that took the partnership to 350. The record may have been updated, but one half of it remained with Watling. He finished unbeaten on 142, his career-best score.

Devashish Fuloria is a sub-editor at ESPNcricinfo