The beleaguered All Blacks have been hit with another body blow, with in-form hooker Keven Mealamu ruled out for the rest of the international season.

Mealamu left the field late in the All Blacks' 31-19 defeat to the Springboks in Durban last Sunday morning after rupturing a chest muscle.

All Blacks doctor Deb Robinson said Mealamu underwent an MRI scan in Auckland yesterday which confirmed a ruptured major tendon on the left side of his chest.

"It's incredibly disappointing for Keven but he is in a positive frame of mind and will undergo surgery on Friday," Robinson said.

Mealamu will be out of rugby for a minimum of four months, ruling him out of the remainder of the Tri-Nations as well as the All Blacks' end of year tour.

It leaves Andrew Hore as the All Blacks' clear No1 hooker and opens the door for Waikato's Aled de Malmanche as his understudy.

Hawke's Bay's Hika Elliot now comes into the frame for a callup as the third choice rake.

Several All Blacks have been made available for Air New Zealand Cup duty over the next two weeks, All Blacks assistant coach Wayne Smith admitting that it was a backflip decision designed to get players in form.

North Harbour's Luke McAlister, Cory Jane and Tamati Ellison (Wellington), de Malmanche and Brendon Leonard (Waikato), Bryn Evans (Hawke's Bay), John Afoa (Auckland) and Tanerau Latimer (Bay of Plenty) are all available this weekend.

Piri Weepu, Neemia Tialata and Rodney So'oialo (Wellington), Kieran Read (Canterbury) and Jason Eaton (Taranaki) are available for round three.

The All Blacks will hold a one-day training camp in Auckland next Wednesday before assembling in Sydney on August 16 to prepare for the Bledisloe Cup test against Australia on August 22.