There were a mountain of milestones yesterday.
Suffice to say Watling reminded everyone he is perhaps the best wicketkeeper-batsman in the test game; Williamson showed why in the not distant future he will become New Zealand's most successful batsman.
His 242 not out, as part of an unbroken 365-run stand with his good mate Watling, lifted him past 3000 test runs quicker than Martin Crowe and Ross Taylor.
His test average is 45.96, higher than any New Zealand batsman with a minimum of 20 innings.
They did their business in contrasting styles. Williamson had the luck - four chances were wasted by Sri Lankan sloppiness in the field - but batted with poise and style.
Watling didn't give a chance and while he bided his time in the morning with a century beckoning, he again demonstrated his high qualities of resilience and skill, especially in a jam, which New Zealand were in when he arrived in the middle, at effectively 24 for five.
"He is such a fighter in everything he does," Williamson said of Watling. "He works so hard off the park, and it's just great to see him achieving what he is at the moment."
They enjoyed batting together. "It was pretty cool," Williamson said as they buried Sri Lanka's hopes.
Williamson - whose tendency is to deflect talking about himself - is an unflustered, composed type. He drove expertly and kept the board ticking over.
His is a simple batting philosophy. He doesn't overcomplicate and he insisted last night he does not avidly peruse statistics.
Say, catching Crowe's 17 hundreds, currently eight away.
"Not at all. You just have the team as your focus and that keeps you going. We needed to bat as long as we did. That was very much the motivating factor.
"Talk about 100s or 200s, it's great to get them but it's more important to keep going to put the team in a better position." Still, it will happen. If he maintains his present rate, stays injury free, it could be by the end of 2016.
In his past 19 test innings, the man who began his test career four years ago with a hundred in Ahmedabad has scored five centuries, in the contrasting environments of Auckland, Jamaica, Barbados, Sharjah and now Wellington.
Of the 12 batsmen ahead of him in test runs for New Zealand, only two, McCullum and Taylor, are active.
Ifs, buts, maybes. They're engaging talking points but are certainly not hard currency and Williamson most likely figures the important thing is to keep doing what he is.
Watling's test average is up to a robust 37.57. He's now the only player to have figured in the two highest partnerships for any wicket in test history.
Wicketkeepers are not dissimilar to rugby halfbacks. They are a pulse for the team and Watling fits that.
He is a key figure in this team's success, which is why they relished his individual success yesterday.
Williamson, blunders and history combine to dash Sri Lanka hopes
Hail the match-saver ... teammates applaud Kane Williamson as he returns to the pavilion after New Zealand's declaration. Photo / Getty Images
Sri Lanka started yesterday at the Basin Reserve with high hopes, but it all went rapidly wrong for them.
They didn't help themselves - wicketkeeper Prasanna Jayawardene botched two opportunities presented by Kane Williamson.
The first was a dropped catch off spinner Rangana Herath at 104, the second a ham-fisted stumping attempt at 233 from the same luckless bowler.
By then, of course, the horses had fled down Cambridge Tce, Sri Lankan heads were drooping and the idea of victory and squaring the rubber was fading fast.
Then came an unexpected glimmer of hope with Brendon McCullum's declaration after tea, when New Zealand had a 390-run lead.
The idea of batting on and on was probably anathema to a man who likes to play his sport with an eye for opportunities.
It clearly surprised his batsmen too.
"BJ and I were quite content to keep ticking it along and Brendon thought it was best to declare. He was waving his arms so that's fine," Williamson said of the decision.
Williamson shied away from talk that he was a big chance to get to 300, and follow in McCullum's footsteps from a year ago on the same ground. That was a long way off, he averred. Nevertheless the way he was going, he was a real chance.
Sri Lanka's bowlers tried hard, but skipper Angelo Mathews didn't bowl himself all day and some of his field settings were, ahem, eyecatching.
Still, when you're under the pump, needs must.
Now they'll start today needing 345 more to pull off what would be a stunning victory. It would be 113 runs more than the best fourth innings winning chase on the ground.
New Zealand need nine wickets. The pitch is good. But Sri Lanka will figure they're not without a hope - especially if Kumar Sangakkara retains his liking for the ground, on which he's got two of his three hundreds in New Zealand.
He will be New Zealand's worry. Sri Lanka need the win and Mathews said before the game 1-0 or 2-0 didn't make much difference. You lose either way.
Will they be good enough? History says no.
NZ's leading test centurions
17
Martin Crowe, 131 innings, average 45.36
12
Ross Taylor, 113 innings, 45.4
12
John Wright, 148, 37.82
11
Nathan Astle, 137, 37.02
11
Brendon McCullum, 159, 38.87
9
Stephen Fleming, 189, 40.06
9
Kane Williamson, 71, 45.96
