Sonny Bill Williams has been cleared to play for the All Blacks in the opening two Bledisloe Cup tests against Australia and will join them in training in Auckland today

Williams' new Japanese club Panasonic Wild Knights granted the New Zealand Rugby Union permission to play Williams over the next fortnight for tests against the Wallabies in Sydney and Auckland.

The special deal was sealed last night and Williams is now in camp with the squad, providing cover for the injured Conrad Smith.

Given his form it seems certain Williams will pair up in the midfield with the experienced Ma'a Nonu.

"It's what we expected, but we knew it was going to take a bit of time, and we are now all looking forward to preparing for Saturday's challenge," All Blacks coach Steve Hansen said.

"We want to express our gratitude to the three parties involved in getting Sonny available for the All Blacks - Sonny's agent Koder Nasser, the NZRU and particularly the Panasonic Wild Knights - for their roles in allowing us to select him."

Williams' All Blacks career looked set to end on 17 tests until Hansen sent out an SOS, believing New Zealand should make use of the Chief star's skills against the Wallabies while Smith recovered from recent eye surgery.

That began a lengthy negotiation process between the NZRU and the Wild Knights with insurance and medical clearances at the heart of getting Williams released on a special short-term deal after his Kiwi contract finished following the Super Rugby season.

Williams is joining the Japanese club on a 12-match deal reported to be worth more than $1m before he returns to rugby league with the NRL in Australia next year.

Williams, a World Cup winner, capped his one-season stay at the Chiefs with a Super Rugby title, scoring the last try in the final win over the Sharks.

The 27-year-old has been in outstanding form for the Chiefs, building his game under the guidance of coaches Dave Rennie and Wayne Smith.

He didn't hesitate to put his hand up when asked to stay on and play for the All Blacks.

He has only played the Wallabies twice in minor roles. He got 12 minutes off the bench in the 30-14 Bledisloe Cup sealer in Auckland last year and then playing just three minutes as a substitute in the World Cup semifinal win at Eden Park before he was yellow carded for a dangerous tackle on Quade Cooper.

It seems likely that Williams will slot in at second-five against Australia in Sydney with Nonu playing at centre.

The All Blacks name their team on Thursday afternoon and fly to Sydney that evening.

- © Fairfax NZ News