"We're disappointed because Bundee is a big part of this squad, we're disappointed for him. He's nowhere near a dirty player," Easterby said.
"He was sanctioned on the day and we lost him for a large part of the game. So we're disappointed with lots of different things but mainly for Bundee. We're lucky we have a really good group of players in that midfield and he is one of those.
"We'll be disappointed if we don't get to use him. He was pretty upset about the decision and rightly so.
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"He's a good trainer anyway but he will be fully focused on trying to prepare the lads in the best way possible for the game on Saturday. There's no better man for knowing how the Kiwis work and how they might be approaching this. He's a big part of this group and will continue to be whatever the outcome of the report.
"At the moment we're having to take the course of action that Bundee potentially won't be available to play for us this weekend."
Robbie Henshaw, who scored the match-winning try in Ireland's historic victory over the All Blacks in Chicago in 2016, is now expected to start in the Irish midfield alongside the versatile Garry Ringrose, with Chris Farrell potentiality offering cover off the bench.
All Blacks assistant coach Ian Foster predicts Aki's absence won't alter Ireland's approach.
"They've got some great midfielders and he's one of them," Foster said of Aki. "Their role definition is pretty strong so whoever plays there is going to play well."
Easterby refused to bite when questioned on whether the All Blacks may attempt to tactically trick Ireland, as Steve Hansen slyly suggested in reference to Joe Schmidt's many trick plays.
"There's no game you don't go into where you try and manipulate the opposition," Easterby said. "Whether that's setting up a different way in a certain situation on attack or defence. I have no doubt they'll have something we haven't seen before and we'll have something they haven't seen before.
"It's something that is part and parcel of the game these days. Every game is analysed. There's a lot of work that goes on in the background to try and figure out how teams play the game but ultimately it's about being physical and trying to impose your game on the opposition."
Quarter-final draw
• England v Australia, Saturday, 8.15pm, Oita
• All Blacks v Ireland, Saturday, 11.15pm, Tokyo
• Wales v France, Sunday, 8.15pm, Oita
• Japan v South Africa, Sunday 11.15pm, Tokyo