All Blacks lock Ali Williams is to undergo knee surgery and will be out of rugby for at least eight weeks.

All Blacks Doctor Deb Robinson said: "Ali developed a sore right knee over the last couple of weeks and a scan has revealed that he has a flap of loose articular cartilage which will require surgery. He will see a surgeon this week in Auckland."

The injury is in the same knee which Williams had an operation on in the off-season but Dr Robinson said it was a new injury.

"It's obviously disappointing for Ali to have this new injury but he is expected to make a full recovery. Once he has had the surgery, we will have a clearer idea of how long he will be out of rugby but it he is expected to be out for a minimum of eight weeks."

Meanwhile, Chiefs loose forward Liam Messam is to join the All Blacks squad as a replacement player.