There had been positive vibes that Williamson would have recovered sufficiently from the broken thumb he sustained in Bangladesh - Bruce Edgar, the national selector, said he was at 95% last week - but it has been decided that it is not a risk worth taking at the start of a long home season.
Williamson batted in the nets without too much discomfort on Sunday, but following a fielding stint, his thumb began to stiffen up.
"It was pretty close, it was a tough decision, but in the end it was just a touch too early for Kane," Brendon McCullum said. "But Aaron has been in such good form and knows these conditions well. We thought he'd be the better option in this Test rather than force Kane back
"He batted yesterday in the nets and didn't feel a great deal of discomfort , but with then doing some fielding then going back into the nets it stiffened up. He probably could have played, but in the grand scheme of the season we have in front of us and how valuable he is to us we saw it as a safer option by allowing him to miss this one and give him another week to recover."
It means that Redmond will add to his seven Test caps, the previous of which came against Australia at Adelaide in 2008. He was the leading Plunket Shield run-scorer last season with 941 runs at 55.35, and was touted as an option for New Zealand when Peter Fulton was recalled to face England. This season he has begun in similarly healthy manner with 271 runs at 67.75 from two matches which again puts him top of the list.
"It's a nice story," McCullum said. "I thought he did a pretty good job for us when he last played and was probably a bit unlucky to have been axed back then. He had a tough year a few years ago when he was captain of Otago and his response since then has been brilliant. It's another one for the older guys in first-class cricket, showing that the door is never shut."
McCullum was also feeling more positive about himself, although conceded his back remained stiff. He admitted to some "dark thoughts" after returning from Bangladesh where the end of his career briefly passed through his mind. While he knows injury may yet curtail his playing days before he would like them to, he is now hungry to resume the challenge of improving New Zealand's Test standing.
"Post Bangladesh its been pretty well reported I took some time to have a think about things," he said. "I know my test performances haven't been up to standard of late. Couple that with the slight injury and you start to have some pretty dark thoughts but when took over this job had some big visions for this team and how I fitted into that.
"That certainly hasn't changed. Just because you go through a few tough times doesn't mean you should change your goals. I'm very determined to lead this team strongly from the front. And that starts with performance."
McCullum is also well aware of the chance presented to his team. Some of the West Indies players are still battling jetlag and there has been scant preparation time for those coming from India.
"It's a great opportunity for us. The placement of the Test match in Dunedin as well - while I'm very fond of Dunedin it's not the most tropical place in the world - and from where they're from they may not be entirely comfortably if we get those southerlies coming in. They are a very good cricket team and experienced in a range of conditions, so we are very respectful of how good they'll be but we do see it as a good opportunity to get us under way in the series and the summer."
Andrew McGlashan is an assistant editor at ESPNcricinfo