New Zealand wrapped up a 2-0 test series win over Sri Lanka, winning the second match by five wickets at Seddon Park today with more than a day and a half to spare.
The hosts began the fourth day at 142 for five, needing a further 47 runs, and KaneWilliamson and BJ Watling completed the job without losing another wicket.
It took to 13 the number of successive home tests without defeat for New Zealand. Their last loss was also at Hamilton, against South Africa in 2012.
Williamson guided New Zealand to the win with his 13th test century, finishing unbeaten on 108 while Watling hit the winning run to finish on 13.
Sri Lanka needed to remove Williamson quickly to have a chance but from the moment when he despatched the second ball of the day to the square leg fence he closed the door on the tourists' hopes.
It was Williamson's fifth century this year, a New Zealand record, and leaves him level with team mate Ross Taylor and four behind the overall leader Martin Crowe.
Williamson also overtook captain Brendon McCullum's New Zealand record of most test runs in a year today. McCullum made 1164 last year, while Williamson's mark stands at 1172.
And to complete his day, only Australian Ricky Ponting (twice) and Sri Lanka's Kumar Sangakkara have scored more international runs in a year than Williamson. But the New Zealander will have a chance to overtake one of Ponting's marks in the three remaining ODIs this year.