The troubled All Blacks suffered a big setback on Wednesday when hooker Keven Mealamu was ruled out for the rest of the year with a ruptured chest muscle.

Mealamu was injured after he came on as a replacement in the Tri-Nations Test against the Springboks in Durban last weekend.

The All Blacks have now suffered three losses from six outings this year and are only halfway through the season. The last time they lost three Tests in a year was 2000.

The loss of Mealamu will put further pressure on the already depleted front row ranks. The burly Chiefs hooker Aled de Malmanche is likely to deputise for Andrew Hore.

All Blacks doctor Deb Robinson said Mealamu had undergone a chest scan after returning from South Africa, confirming he had ruptured his pectoralis major tendon on the left side of his chest.

The injury will keep Mealamu sidelined for the rest of the Tri-Nations series as well as the end of year tour.