The All Blacks are confident of having injured skipper Richie McCaw back for the final Bledisloe Cup Test against Australia in Dunedin in October.

They also have their fingers crossed that the openside flanker could return a fortnight earlier for their Rugby Championship match in South Africa on October 6 (NZT).

McCaw limped off in the 60th minute of his 119th Test – the 28-13 win over Argentina in Hamilton on Saturday night – with medial ligament damage in his left knee.

The early prognosis is that he will be out for four to five weeks and, if that proves the case, he will miss the fixture in Johannesburg.

Coach Steve Hansen says McCaw, who won’t require surgery, will stay with the squad next week ahead of the Springboks Test in Auckland.

“By the end of the week, we’ll have a pretty good idea, so hopefully, maybe, he might get the second South African game,” Hansen said on Sunday.

“‘Doc’ thinks he will definitely get the third Bledisloe game.”

The All Blacks have already retained the trans-Tasman trophy after winning the first two clashes against the Wallabies.

McCaw’s injury has led to Crusaders teammate Matt Todd being brought into the squad.

It also means Sam Cane is in line to wear the No.7 jersey at Eden Park in what would be his first game against South Africa.

Hansen has plenty of faith in the 21-year-old Chiefs player’s ability to meet the challenge.

“Yep, he’s ready for it,” he said.

“Sam’s had a pretty good apprenticeship so he’s ready to rumble.”

Cane played all but eight minutes of the three-Test series against France in June when McCaw was on his six-month break from rugby.

Hansen said inside centre Ma’a Nonu and blindside flanker Liam Messam would both be available for selection against the Springboks.

Nonu could have been used against the Pumas but was given extra time to get over an ankle injury.

Messam has recovered from the hamstring problem that has kept him out of the Rugby Championship so far.

His return poses an interesting problem for the selectors, with Messam’s replacement in the No.6 jersey over the past three Tests, Steven Luatua, showing his huge promise.

“He’s gone very, very well, so it will be a tough choice,” Hansen said.

“It might come down to how we manage the bench, whether we start Liam or bring him off the bench and take the risk that we’ve already subbed Steven.”

Meanwhile, back-up five-eighth Aaron Cruden remains in doubt with his knee injury and will be checked during the week.