All Blacks captain Sam Cane and hooker Dane Coles have been ruled out of New Zealand's Autumn Nations Series matches against Wales, Scotland and England.
Cane suffered two cheekbone fractures in Saturday's 38-31 win over Japan in Toyko and returns to New Zealand along with Dane Coles who was scratched from the game minutes before kick-off.
A calf muscle tightened up for Coles and the hooker also didn't travel to Europe with the squad.
All Blacks XV squad members Billy Harmon and Asafo Aumua have been called into the squad to replace the pair, the former earning his first call-up to the squad.
Elsewhere in the squad, Patrick Tuipulotu and back Damian McKenzie will rejoin the All Blacks XV to play Ireland A having provided cover for the Barretts who were unavailable to the All Blacks for the Japan test due to family reasons.
Foster said it was disappointing to lose two of their leaders in Cane and Coles, especially after the first game, but it was another adjustment the All Blacks have had to keep making.
"It will creates a great opportunity for the likes of a Dalton Papali'i and he's in good form. It's the reality of rugby, you always want to get through your first couple of games injury free. It hasn't worked out this way, and it doesn't change the challenges coming up."
In relation to lock Brodie Retallick's red card for dangerous play, Foster said they would enter into the judicial process by presenting a rugby case and see what unfolded. The hearing is likely to be on Tuesday.
The All Blacks kick their Northern Hemisphere tour off with a clash with Wales at the Principality Stadium before heading to Murrayfield to tackle Scotland. Their 2022 season is completed with a clash with England at Twickenham on 13 November.