He did not bowl or bat in the last match but will carry the drinks for the second one-day international against Pakistan at the Queenstown Events Centre today.
McCullum is a victim of rotation and makes room for top-order batsman Jamie How.
You cannot blame the Black Caps for wanting to experiment with their line-up four weeks out from the World Cup.
But Black Caps captain Daniel Vettori acknowledged it was a tough call on McCullum.
"I think Nathan, arguably, has been our best one-day player over the last year," he explained.
"He has done exceptionally well for us with bat and ball and everyone knows he is a great fielder.
"So it is not a form thing. It is just slotting Jamie in and giving us the right balance. But I think everyone knows Nathan is in our first-choice team."
Cold comfort for McCullum should How score plenty batting at the unfamiliar position of No 4.
Pakistan is also likely to make changes, with experienced strike bowler Umar Gul and left-armer Wahab Riaz coming back into the side.
Whom they replace is not clear but Pakistan captain Shahid Afridi indicated their return during a brief press conference yesterday.
"We will definitely make some changes because this is the only time we have before the World Cup," he said.
"Wahab Riaz and Umar Gul bowled too many overs in the test match so we gave them a rest in the first game."
Afridi is confident his side can bounce back from what was an underwhelming performance in Wellington.
Blitzed by nine wickets, Afridi said his side lacked patience.
"Individuals are struggling to play 50 overs but I think the boys realise how important our starts are ...
"But we are very confident and positive that we can come back."
In stark contrast, Vettori had the rare opportunity to talk his side up following the comprehensive victory.
"We were really pleased with the performance, more than anything, and that is what we have been searching for.
"I think the result, in terms of how comprehensive it was, is not always easy to maintain.
"But that performance we've put in is our standard for the rest of the summer and we need to make sure we live up to it in this game here."
Vettori was careful not to read too much into the one-sided opening encounter.
"Every game you play you have to reset and tell yourself it is about winning and doing all those good things, particularly around practice.
"Hopefully, the way we have trained, will allow us to play well in the game."
Cricket is a funny game. Hero one minute, villain the next.
But the Black Caps have been stuck in the latter role - the pointy moustache, hand-wringing, cackling villain since their 4-0 drubbing in Bangladesh and horrendous 11-match losing streak which they broke with the win against Pakistan.
There has been talk from the camp about winning back public support.
A disappointing crowd of 8000 watched the team drill Pakistan on Saturday.
And there is unlikely to be much of a crowd today.
It is midweek match in a resort town, and it is hard to imagine too many curious Americans or Japanese flooding through the gates.
That said, it is a good opportunity for the Black Caps to slap a band aid on their poor public perception.
Of course, it would be the sort of plaster that comes with pictures of Spongebob Squarepants on it.
You know, the type which comes unstuck two minutes after you stick it on the wee ones.
But a win would give the Black Caps a 2-0 lead and make it very difficult for Pakistan to win the six-game series.
That would be progress, which is all you can ask.
