All Blacks scrumhalf Tawera Kerr-Barlow has been ruled out of rugby for at least six months with a serious knee injury.

The injury occurred towards the end of the All Blacks' loss to the Springboks at Ellis Park on Saturday as he was attempting to clear the ball upfield. He played on for five minutes before eventually succumbing to the injury.

He will require surgery on the knee, and could face up to nine months on the sidelines.

'He's done his ACL,' said All Blacks coach Steve Hansen. 'He's torn the back of his hamstring off and has done his medial ligament. He needs an operation when we get home.

'Sometimes they do two operations but he's about a six-to-nine month recovery so it's pretty major.

'When you saw it on the replay it was pretty horrific. He's a brave boy to be able to get up and do what he did, gutsy as hell.

'He'll have to work hard at his rehab and I'm sure he'll come back. He's a tough kid.'

The injury will provide Hansen with a selection headache ahead of the Bledisloe Cup match against Australia and the subsequent tour to the United States and Europe.

Hansen also revealed that utility back Ben Smith will be rested for the dead rubber against Australia after playing every minute of the Rugby Championship.

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