Aaron Cruden and Beauden Barrett are out of Saturday's Bledisloe Cup rematch in Wellington.
Scans have revealed damage to the posterior cruciate ligament in Cruden's right knee which will rule him out of rugby for two to six weeks.
Barrett has a slight calf strain and is expected to be fit for the test against Argentina in Hamilton on September 7.
And in further bad news, lock Luke Romano has been ruled out of the remainder of the Rugby Championship with a groin injury.
All three players suffered their injuries during the All Blacks 47 - 29 win in the opening Bledisloe Cup Test in Sydney.
The twin injuries to the two incumbent first five eighths creates a similar situation to that faced by the All Blacks during the 2011 Rugby World Cup.
With Dan Carter already on the sidelines with a calf injury, Highlanders pivot Colin Slade and Crusaders back Tom Taylor will come into the mix for the second Bledisloe Cup match.
Slade, with 10 test caps, will be the early favourite to fill the crucial No. 10 duties.
Romano has torn his right adductor tendon and is not expected to be available until the All Blacks European tour in November.
Hurricanes lock Jeremy Thrush is the logical replacment in the All Blacks match day 23.
While the situation at first five eighth will dominate public discussion, All Blacks coach Steve Hansen's immediate thoughts were with Romano.
''It's obviously hugely disappointing for Luke but he is a strong character and is already planning his rehab with our medical staff.
''We hopefully will have Beauden ready to prepare for the Argentina test, while Aaron will start his knee rehabilitation later this week, which will give us a better indication of when he will be back playing.
"It's an exciting time for the replacement players Tom Taylor and Colin Slade and it's also a challenge now for the rest of the team to make their entry into the side as seamless as possible."
- © Fairfax NZ News
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