New Zealand will be confident of repeating that win after inspecting a green pitch confirmed today, although those 20m can be misleading pieces of turf.
Sri Lanka seemed to figure the pitch had been teed up with New Zealand's fast-medium bowlers in mind, at least judged by coach Jerome Jayaratne's comments yesterday.
It had changed only marginally from the billiard table green when Jayaratne made his "doctored" comment.
Groundsman Karl Johnson quipped that his pitch is like a bride who ''doesn't put the dress on until the day of the wedding". Translation: wait and see this morning.
The initial thinking will be bowl first, but tests are played over five days not one. Then again, do piles of damage on the first day and you can take the fifth day out of the equation.
''I think whoever wins the toss it's pretty clear what they may look to do," Williamson said.
''But we've played on the surface a lot. It always is green, in fact every surface we play on here starts very green and I think it will be a good cricket surface but if it swings that's when it offers more to the bowlers.
''I'm sure it will be tough early on and it might offer something throughout with the hard new ball."
There was no dollar each way talk from Sri Lanka's captain Angelo Mathews - it's bowl first for him.
There's sure to be a temptation to keep the heat on Sri Lanka's vulnerable batting group, in which there's a mix of experienced performers and some very green in test playing terms.
Williamson said teams must guard against pre-conceived expectation.
''It can be a distraction sometimes. Like on a spinning wicket, sometimes the straight ball gets you out and getting your head around that philosophy of a seaming wicket, if you completely change your game sometimes you over-think it.
''If we apply ourselves I'm sure there are runs to be had out there."
Thus speaks the local man, who has racked up 1063 runs at 88.58 this year in tests, the fifth highest on aggregate, but by 25 runs the highest average of the top five.
There's a statistic which should give New Zealand considerable pleasure. They have not been beaten at home for 12 tests, six won, six drawn.
However, if Sri Lanka are looking for a silver lining in that, the last three test losses, to Australia, Pakistan and South Africa, have all been at Seddon Park.
''That's a nice stat," Williamson said of the dozen. ''But it's important that we keep bringing ourselves back to the start, the basics, and how we go about our business each time."
As for Sri Lanka, they are a work in progress, certainly in the batting department.
The key figures - Dinesh Chandimal, captain Angelo Mathews and opener Dinesh Karunaratne - are easy to identify. But there were signs in Dunedin they are learning.
''Test cricket is a test of patience and skill," Jayaratne said.
''I think we have the skill, it's just the patience and picking the correct ball -- that's what they have to make their mind up about.
"Our guys have talent and the skill, but the adaptation is the most important thing."
Sri Lanka are likely to field an unchanged XI from Dunedin, Mathews reasoning yesterday young players should not be discarded on the strength of one ordinary outing.
Their seamers squandered the best bowling conditions in Dunedin on day one. From then on they were on the back foot. They can't afford similar wastefulness if they are bowling today.
