Back problems resurface after Brendon McCullum's hard landing on Hagley Oval
Brendon McCullum's successful attempt to save a boundary may prove costly after all with the Black Caps captain in doubt for the potentially series-clinching ODI with Sri Lanka in Nelson on New Year's Eve.
Angelo Mathews' 17 runs were immaterial as New Zealand bludgeoned their way to a 10-wicket victory in the second leg of the Christchurch double header at Hagley Oval on Monday, though his stroke off Mitchell McClenaghan midway through the ninth over could yet be beneficial for the tourists.
McCullum landed awkwardly when restricting his counterpart to a three, aggravated his long-standing back injury and took no further part in the match as predecessor Ross Taylor assumed control because vice-captain Kane Williamson continues to recuperate from a knee injury sustained during the second test in Hamilton.
Ultimately McCullum's power hitting was not required as Martin Guptill demoralised the Sri Lankan bowlers with a remarkable unbeaten 93 from just 30 balls - a strike rate his retirement-bound captain would have struggled to emulate.
McCullum, who has one last opportunity to bat in his adopted home town when his farewell tour ends with the second Australian test in February, received treatment and will be monitored ahead of the first of two games at Saxton Oval.
Black Caps coach Mike Hesson confirmed McCullum would travel north with the squad on Tuesday while Tom Latham, who joined the squad as cover for Williamson, will remain on tour.
"We're hopeful he'll be able to take part in Nelson though if he's not right we've got cover there to deal with that.
"He had a stiff back just before the game started. Obviously diving for that one stirred it up. It's a disc issue and history suggests it's 24 to 48 hours, but obviously every disc reacts a little bit differently."
McCullum, 34, has persevered with back pain over the latter stages of his international career - not that it has impeded his strokeplay.
He slammed 55 from 25 balls as the Black Caps opened their five-match series in style with a seven-wicket win on Boxing Day - his absence from Monday's run chase might have concerned the crowd though Guptill swiftly provided the entertainment with his audacious mix of slogging and orthodox shots.
Meanwhile, New Zealand's quickest bowler Adam Milne was only rested as a precaution after reporting difficulty with the heel injury that ended his World Cup campaign at the quarterfinal stage.
He should be fit for selection as there were no plans to retain Matt Henry, who returns to domestic one-day duty with Canterbury for Wednesday's clash with Otago in Alexandra. Williamson is also tracking positively for a return - a prognosis to give the Sri Lankans more discomfort.