The All Blacks' depth at openside flanker could come under the microscope following a hand injury suffered by Canterbury No.7 Matt Todd.

Eight-Test flanker Todd fractured his left hand during Canterbury's successful Ranfurly Shield defence against Otago and will be in a splint for about a month, ruling him out of rugby for that period.

The injury coincides with concern over the fitness of first-choice New Zealand No.7 Sam Cane, who failed a head injury assessment early in Saturday's Bledisloe Cup Test win over Australia in Dunedin.

Todd had been expected to be drafted into the All Blacks squad as cover for the next two Tests in the Rugby Championship, both on home soil.

They face Argentina in New Plymouth on September 9 and South Africa in Auckland a week later.

Hurricanes dynamo Ardie Savea will be the only fit specialist openside flanker in the squad if Cane is ruled out.