New Zealand coach Steve Hansen will be down to his fourth-choice fly-half for Saturday's Bledisloe Cup clash with Australia in Wellington.
Aaron Cruden is set to be sidelined for up to six weeks with an injured posterior cruciate ligament in his right knee, while his deputy Beauden Barrett is out of action for at least a week with a calf strain.
Both picked up injuries in New Zealand's 47-29 win over Australia in Sydney at the weekend, after which Cruden was named man of the match.
Colin Slade and Tom Taylor joined the All Blacks squad this week as a precautionary measure but will now be considered for selection to wear the No.10 jersey at Westpac Stadium.
With 10 Test caps, Slade is likely to be given the nod to start with Taylor set to provide cover from the bench.
First-choice pivot Dan Carter remains sidelined with a calf problem of his own, while Barrett could be in line to return against Argentina on 7 September.
The All Blacks will also be without Luke Romano for the remainder of the Rugby Championship after he tore his right adductor tendon in the win over Australia.
"It's obviously hugely disappointing for Luke but he is a strong character and is already planning his rehab with our medical staff," Hansen said.
"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."