Tom Blundell is on standby to replace Henry Nicholls against England if the New Zealand batsman is ruled out of the remainder of the first Test.
Nicholls was struck on the helmet by a bouncer from England paceman Jofra Archer in the penultimate over on day two at Bay Oval in Mount Maunganui.
The 28-year-old was able to remain at the crease and was unbeaten on 26 at stumps, with the Black Caps 144-4 in reply to the tourists' 353 all out.
Nicholls will undergo concussion tests and Blundell will replace him if he is unable to continue.
New Zealand paceman Tim Southee said: "He's a pretty tough character so he'll rest up tonight, a couple of Panadol and be back out there.
"He'll be assessed later on tonight and again in the morning, that's the protocol.
"He's shaping up all right at the moment so fingers crossed he'll be right."
Sam Curran took the big scalp of Kane Williamson for 51 after also removing Tom Latham.
Ben Stokes earlier top-scored with 91 for England, with Southee taking 4-86 in an opening match of the series that is nicely poised.