Williamson's side returns to cricket action in Galle exactly a month after their cruel World Cup defeat by England, with the Kiwi skipper welcoming the addition of a new potential title.
“It's a welcome addition to the Test format, bringing that context into every Test match that you play,” Williamson told reporters.
“Every time you play any team it's very, competitive, but now there's that added carrot where in two years time everyone is vying for an opportunity to play in a Test Championship final, which will be a really exciting thing to be a part of.”
New Zealand are currently ranked number two in Tests and a 2-0 series win over Sri Lanka will help them claim the top spot from India.
“If that happens, that would be great. The thing with rankings is that they fluctuate throughout a season, and are purely a reaction to the cricket that you're playing,” said Williamson.
“For us, we're just focused on cricket because that gives us the best chance of success. We're looking forward to the challenge here against Sri Lanka.” The tourists' hopes could be hit by bad weather as rain is predicted on the first two days of the Galle match.
On paper, New Zealand are the stronger side having two players each in the rankings for top bowlers and batsmen.
Sri Lanka, on the other hand, will be looking to build upon their improvement since Dimuth Karunaratne took the captaincy in February and they became the first Asian nation to win a Test series in South Africa.