Aaron Smith is due to link up with the New Zealand squad later today but is unlikely to feature against Ireland.
The 101-cap scrum-half was added to the squad as injury cover following a head knock to Brad Weber early in last weekend's 47-9 win over Italy.
"Aaron is only arriving Wednesday, he doesn't know what the plan is," said New Zealand assistant coach John Plumtree.
"So it's pretty unrealistic to think that Aaron is going to be playing at the weekend."
Weber is going through concussion protocols and is considered a doubt to play, while young scrum-half Finlay Christie nursed a sore neck after the Azzurri game.
However, TJ Perenara is fit and Plumtree expects Christie would be available for Saturday's clash in Dublin (3.15pm, live on RTÉ) after getting through training on Tuesday.
Plumtree said that apart from tighthead prop Angus Ta'avao, who is still recovering from an elbow injury, the All Blacks had no other injury concerns with former Connacht target Sevu Reece considered "grand".
'The most important thing is that we win and that's what we're judged on' - @irishrugby captain Johnny Sexton looks ahead to @allblacks challenge #RTERugby #RTESport #IREvNZ pic.twitter.com/n5avyvNvk7— RTÉ Rugby (@RTErugby) November 9, 2021
Meanwhile, Andy Farrell will name his Ireland team at Thursday lunchtime and there are three New Zealanders in the running to face their native land.
"I'm not sure they'll fear us, mate," replied Plumtree when asked if Bundee Aki, Jamison Gibson-Park and James Lowe’s presence in the Ireland squad might reduce the fear factor around the three-time World Cup winners.
"Ireland will believe that they can beat us. That will be based on how they played last week and their preparation this week.
"We understand that as an All Black team and that’s what excites us as well.
"Those guys know our players. Some of them have played a lot of rugby together and from what I’ve read they’ve gone to some of the same schools and stuff but they don’t know what our plan is, how we train and prepare to play against them.
"They’ll have a bit of insight and a bit of history on some individuals but our plan is our plan and they won’t know it."
Follow Ireland v New Zealand via our liveblog on RTÉ.ie/sport and the RTÉ News app, watch live on RTÉ2 and the RTÉ Player or listen to national radio commentary on RTÉ Radio 1's Saturday Sport.