Flanker McCaw was ruled out for up to five weeks with a knee injury after prop Charlie Faumuina landed on his left leg during a tackle in Saturday's 28-13 victory over Argentina.
All Blacks coach Steve Hansen was hopeful his World Cup-winning skipper might recover in time for the team's Oct. 5 clash against South Africa in the final round of the Rugby Championship, but McCaw is likely to miss the rest of the southern hemisphere tournament.
Matt Todd, who made his test debut in June against France, will join the squad as cover, but Hansen said he had faith in 21-year-old Cane to step up for the All Blacks' blockbuster home clash against South Africa on Saturday.
"He's ready for it, he's played some good rugby for us," Hansen told local reporters of Cane, who was anointed McCaw's successor to the number seven jersey last year.
"He hasn't played a poor test, I don't think, and he's played some very good ones.
"He's comfortable and that's important," Hansen said in Hamilton on Sunday. "A lot of players in years gone by have been, I wouldn't say frightened, but certainly burdened by the expectation that comes with being an All Black.
"Sam's had a pretty good apprenticeship so he's ready to rumble."
Cane started all three tests against France in June, however, McCaw's return to the starting side following a long sabbatical left the Waikato Chiefs loose forward making cameo appearances off the bench in the Rugby Championship.
Following two emphatic opening wins over Australia and a third against Argentina, the champion All Blacks are likely to face a stiffer challenge from the undefeated Springboks.
The South African forwards hammered the Wallabies in their 38-12 victory in Brisbane on Saturday, taking a very simple bludgeoning approach to their work.
Time and time again, the Wallabies were driven backwards in the scrum, tackle and at the breakdown with the loose forward trio of Francois Louw, Willem Alberts and Duane Vermeulen, suffocating any Australian momentum.
Openside Cane is likely to combine with stand-in captain Kieran Read and rookie blindside flanker Steven Luatua for the mouthwatering back-row clash, though Hansen said last year's starting blindside flanker Liam Messam would be in the selection mix after his recovery from a hamstring strain.
The Springboks lead the four-nation tournament on 14 points courtesy of two bonus points for scoring four or more tries twice.
The second-placed All Blacks are on 13 points and the winner of the game at Eden Park will go a long way to securing the title.
Hansen was well aware their performance against the Pumas in Hamilton was less than ideal and had been frustrated at his players' reluctance to kick into open field and put pressure back on the South Americans with a good chasing game.
Hansen's desire to play the game at pace and with width, however, will continue next week.
"They've kept their physicality but they've sped up their game, they're using their backs a lot more and this will be the first time they've had so many bonus points in this competition," he said of the Springboks.
"That's a reflection on how they're using the ball so they're going to be really, really tough."