McCullum said it was a rational decision made between himself, Vettori and coach Mike Hesson.
"We sat around and spoke about how he's feeling. He gave it his best shot but didn't want to let the team down.
"One thing we looked at was 'would we sacrifice the coming few weeks of the Champions Trophy as well?' We decided that was not the right thing for either party.
"He couldn't be certain his body wouldn't flare up again in the coming weeks. It was a thorough process. He gave it every opportunity."
Looking skyward for effect, McCullum said he hoped conditions would play in their favour.
"The wicket looked a touch dry so it's a gamble either way but when you're 1-0 down in a series. It's one we're prepared to take. Hopefully we get cloud cover and our four seamers prosper.
Vettori spent just over half an hour bowling yesterday. He landed the ball on a good length the majority of the spell and got the odd one to purchase on the practice strips cut 50m from the match pitch.
His batting assumed its familiar shape with a full range of on drive slaps, front of square swats and paddles behind square.
New Zealand XI: Brendon McCullum ©, Peter Fulton, Hamish Rutherford, Kane Williamson, Ross Taylor, Dean Brownlie, Martin Guptill, Doug Bracewell, Tim Southee, Neil Wagner, Trent Boult.