"It's going to be a great series, New Zealand have been playing some very good cricket at home and we've got to improve the cricket we play away from home.
"It should be a really hard-fought series."
McCullum, preparing for his world record 100th successive test at the Basin Reserve and his second last before retirement, sang from the same sheet as Smith.
"It definitely wasn't heated between us," he said. "I get on really well with Mitch as well, and also Wadey [Australian wicketkeeper Matt Wade, who became involved in a sharp exchange with Grant Elliott].
"There was definitely no animosity or choice words spoken out there. It was more just discussing the process, that it just wasn't ideal overall."
That second last sentence might be a stretch, but the point is that broadly speaking the players rub along well, allowing for the competitive juices sometimes overflowing in the middle. A touch of spice won't hurt the series either. A touch mind, not a bucket.
Offspinner Mark Craig is back, replacing the injured Mitchell Santner in a change forced by Santner damaging his right foot in the Wellington ODI on Saturday.
Craig was taken to by Australia's quick-footed batsmen, who behaved like sharks sniffing blood when he marked out his runup in the three tests in Australia before Christmas.
Craig was not at his best - his eight wickets costing 64 apiece - but chances were missed off him. He took a timely five wickets for Otago against Wellington in Queenstown at the weekend and he's likely to play.
Otherwise, due respect to the occasional offspin of Kane Williamson, New Zealand will be putting out an all-seam attack, with no specialist spin cover.
That can leave a side three wide, facing the breeze if things go pear-shaped among the seam group. Assuming Craig makes the XI, it will be just his third home test out of 14.
There are eight new faces in Australia's squad from the ODI rubber, including four of the five fast bowlers - Josh Hazlewood the exception.
Several Australian players have been based in Wellington preparing for a series which promises so much, on pitches expected to be greener and bouncier than those in the ODI series.
Australia will reclaim the No1 world test ranking if they win the series 1-0 or 2-0.