Leon MacDonald, who replaced Dan Carter with such aplomb at fly-half against South Africa, has been suffering from a hip injury for the last seven days and was forced to miss training this week.
"Our expectations at this stage are that he has to drop this injury, we don't want him to train until its right," Henry told www.AllBlacks.com.
"We're going to give him a bit of space to do that.
"I'd be surprised if he trained [on Wednesday] but he's close to the action and he's listening to what backs coach Wayne Smith has to say.
"We just have to give him time because if we push him then he's not going to play."
Luke McAlister has been put on stand-by to replace MacDonald if he is ruled out.
Lauaki takes over from Jerry Collins, whose suspension has forced Henry to change a winning team following last weekend's 31-27 triumph over South Africa.
"Our selection reflects that we respect Australian rugby and the Australian team and we all know it will be a hard game at the weekend," Henry said.
"Jerry has had an outstanding international season. It's disappointing he can't finish it.
"It was a logical selection. Sione Lauaki's been in the squad right through, he's been on the bench a lot and he'll be dying for an opportunity."
But the New Zealand coach has decided to drop Rico Gear in favour of Howlett, recalled to the Tri-Nations side after flourishing in the NPC.
The Auckland flyer lost his All Blacks spot earlier this month.
"He's (Gear) had a big year, and we've got a fresh guy, Dougie, who's jumping out of his skin," Henry said. "It's just sensible to play Doug in this game."
Reserve prop Greg Somerville, whose wife is due to give birth to their first child, may also step down.
Assistant coach Steve Hansen said: "We'll give Greg as much time as he needs, he's well versed in what we're doing and how we do it.
"We'll give him the opportunity to go about his business and get back up here.
"In the situation he's in, you have to give people enough space to be able to be happy and still come and perform."
The All Blacks are looking to extend a 19-year unbeaten streak against the Wallabies at Eden Park.
New Zealand team: M Muliaina; D Howlett, T Umaga (captain), A Mauger, J Rokocoko; L MacDonald, P Weepu; T Woodcock, K Mealamu, C Hayman, C Jack, A Williams, S Lauaki, R McCaw, R So'oialo.
Replacements: D Witcombe, G Somerville, J Ryan, M Holah, K Senio, L McAlister, C Smith.