New Zealand number eight Kieran Read will miss the opening weeks of the Rugby World Cup with torn ankle ligaments.
All Blacks loose forward Adam Thomson is also set to miss the opening match against Tonga with an injured elbow.
The pair had scans after picking up the injuries in Saturday's defeat by Australia.
Jerome Kaino, Richie McCaw and Victor Vito are the only fit back-row options remaining in the All Blacks squad.
World Cup rules specify that if an injury replacement is named, then the player replaced is ruled out for the entire tournament.
On that basis New Zealand have decided against replacing either Read or Thomson, and will rely on their locks - Brad Thorn, Ali Williams, Sam Whitelock and Anthony Boric - as back-row cover.
"Obviously it's disappointing to lose two quality players before the tournament starts but they are not out of contention for the latter part of the tournament," said assistant coach Steve Hansen. "We've got enough cover to be able to keep them there and that's the key thing."
All Blacks doctor Deb Robinson explained the nature of the injuries.
"Kieran has torn the ligament between the tibia and fibula at the front of his left ankle," she said.
"While it's still early days in his recovery, with aggressive rehabilitation we are aiming to have him available to play near the end of the round robin [pool matches].
"Adam's MRI scan shows some swelling around the inside of his elbow which should settle quickly."
Read has 32 caps and was New Zealand's player of the year in 2010, while Thomson has 17 caps and can play on either flank.
Henry conceded his decision to rest players for New Zealand's previous Tri-Nations match in South Africa before the decider in Brisbane had back-fired.
The All Blacks will now go into their World Cup opener against Tonga on 9 September on the back of two consecutive defeats.
"There was some consolation in the way we came back and showed some grit in the second half [on Saturday] but [it was] a disappointing game for us," said Henry.
"I just think we've had an unusual preparation for this Test. Some guys stayed in New Zealand and some guys went to South Africa.
"We thought that was the best step going forward into the Rugby World Cup and it didn't gel for some reason or other. It just didn't gel.
"We'll just have to wait and see how this turns out. If there was some [complacency] there, it won't be there now."