The Black Caps assistant coach Craig McMillan admits he has no idea if injured strike bowler Tim Southee will take further part in the three-Test trans-Tasman cricket series.
The Black Caps have called paceman Neil Wagner into their squad after Southee left the field to receive treatment on his back on the second day of the first Test against Australia in Brisbane, and failed to return.
Officials said he was suffering from an irritated disc.
Batting coach McMillan said they would monitor Southee again on Saturday but could not provide an update on whether the strike bowler would be seen again this series.
"Obviously it was a blow. He's got some stiffness in the back which is something that will be monitored overnight and we'll see how he wakes up," he said.
"In terms of answering (whether Southee takes) further part in the series, I can't at this stage."
"We will see how he scrubs up over the next couple of days in terms of his availability."
The second Test starts in Perth on Friday.
The short turnaround ensured Wagner received an SOS.
"Tim will continue to be monitored and assessed over the coming days but it's important we have all of our bases covered," coach Mike Hesson said.
"Bringing Neil into the squad as cover assures us of that."
Wagner has played 16 Tests and taken 58 wickets at an average of 34.48.
He hasn't played for the Black Caps since December 2014.
Matt Henry is the other paceman in the touring party, however he was overlooked for the first Test in favour of Doug Bracewell.
Southee was sent for back scans after day one of the clash in Brisbane.
He bowled a four-over spell in the morning on day two but was clearly restricted.
The paceman later returned to the attack but completed only one over before trudging off the park.
During that over, Southee's 24th, he aborted his run-up and regularly grimaced.
The sight of Southee limping off the Gabba on Friday morning extended the Black Caps' miserable start to the three-Test series.
Heading into day three of the opening Test, New Zealand were 157 for five in reply to Australia's declared innings of 556 for four.
Southee was still the pick of the bowlers with one wicket for 70.