Dave Rennie has confirmed his All Blacks squad is carrying a mounting injury toll ahead of Saturday's Rugby Championship series opener against the Springboks, with four players already ruled out of the tour and two more in doubt.

Prop Ollie Norris is the latest departure, heading home with a cartilage injury to his knee that is expected to sideline him for six weeks. Highlanders prop Saula Ma'u has been called up as his replacement. Norris joins Billy Proctor (shoulder), Caleb Clarke (shoulder) and George Bell (calf) as players whose tours have been cut short.

Halfback cover has also been bolstered with the call-up of Noah Hotham after Cortez Ratima sustained a PCL injury to his knee during the match against the Bulls. Rennie confirmed scans have established the PCL diagnosis but said the All Blacks are still assessing severity over the following 48 hours. Cam Roigard is expected to be fit to start on the weekend, with Kyle Preston available as additional cover if Ratima does not recover in time. Hotham is earmarked to play against the Lions on Tuesday.

Damian McKenzie, who hurt his ankle against the Sharks and missed the Bulls match, remains a concern. Rennie said McKenzie completed a light run on Sunday and continued work with the physio on Monday, with a clearer picture expected within 24 hours.

On the positive side, Rennie expects Will Jordan, Roigard and captain Ardie Savea — none of whom have featured on tour yet — to be available for the Springbok clash.