McCullum has produced spectacular batting on this ground before - his 195 off 134 balls against the same opponents last Boxing Day leaps to mind - and yesterday gave another example of what New Zealand will miss when he departs the international game in February.
Sri Lanka's bowlers were powerless as the pair flew to 108 in 10.1 overs.
In six successive overs, from the fourth to ninth, McCullum and Guptill took 11, 11, 11, 17, 12 and 17 runs. Game over.
Guptill showed how he has become the highest ODI runscorer this year with clean striking around the ground, while McCullum was, well, McCullum.
He's like a diamond; catch him in the right light and he dazzles. There were a couple of miscues early yesterday. Again, that's McCullum. He certainly doesn't always come off, but when he does, you want to be there.
''Watching the two of them bat together is just fantastic," Henry said. ''Over the last 12 months the two of them have taken down some very good attacks."
Once McCullum left to a standing ovation - 55 off 25 balls -- the job was effectively done. Nicholls got the winning runs in a nice cameo to start his international career.
New Zealand extended their ODI home winning run to 11 games yesterday. That reinforces that it's not just in the test game that they are a formidable team in their own conditions.
Sri Lanka's coach Jerome Jayaratne was moved to offer an apology after the match.
''Sorry to the New Zealand public that we let all these people down that made their way here on Boxing Day," he said.
"They would have expected a stronger game and us to be more competent. We were just not up to it today."
Earlier the New Zealand seamers did well. At 27 for five, then 65 for six, Sri Lanka had no price.
Henry snared the headline figures, but Adam Milne looked sharp, getting to 150kmph early in his first spell; Doug Bracewell played an important part - he's taken seven wickets at 17 in his last three ODIs - while Mitch McClenaghan, unlucky when Nicholls spilled Sirawardena, then on the end of some rough treatment, bounced back well.
Sirawardena is 29, a late developer, but there's much about his batting for Sri Lanka to enthuse over. His determined stand of 98 with veteran swing bowler Nuwan Kulasekera was the only noteworthy item in their innings.
New Zealand's fielding wasn't as sharp as it might have been so, as ever, there are coaches like to call work-ons.
''Sri Lanka are a great side and of course they'll come back stronger," Henry said.
''Everyone has days like this, but I'd expect them to come out with full heat in two days' time."
No Williamson, Boult or Southee, but this is still a pretty capable New Zealand side. The teams meet again tomorrow.
SCOREBOARD
WAGONWHEEL
MANHATTAN