Sonny Bill Williams as the new Reuben Thorne when the Crusaders bid for the inaugural Super 15 rugby crown?

That's seemingly incongruous notion has been floated since the Bulldogs ball-playing second rower abandoned the National Rugby League for French rugby in 2008 - and All Blacks assistant coach Wayne gave the concept further credence today.

The All Blacks coaches have been so impressed with the 25-year-old's physical attributes, Smith envisaged Williams could be utilised on the blindside flank of a Crusaders loose trio already comprising Kieran Read and Richie McCaw.

"During Super rugby he may have a crack at other positions, he had six weeks at (No) 6 for Toulon," said Smith as the squad adjusted to a frigid Edinburgh ahead of Sunday's (NZT) test with Scotland at Murrayfield.

"He's a different sort of athlete, he's an athlete where we've just go to see what best suits him - and the team."

Williams' trial on the side of the scrum in France was not considered a success and he reverted to his preferred role in midfield - the ideal setting for his inevitable tackle-busts and freakish offloads.

Williams made his test debut at centre against England last weekend, and supplied one trademark offload to instigate Hosea Gear's maiden test try.

He was then guilty of fading in an out of the game at Twickenham - not that a mixed performance should coast against his selection for the second leg of the All Blacks Grand Slam attempt.

It is possible Williams will move in a spot to second five-eighth against the Scots so he can continue his rugby education alongside Conrad Smith, providing New Zealand's first choice centre has recovered from a minor hamstring strain.

Despite Williams critical role in Gear's try and England's inability to expose him defensively, Smith said his work at the tackle still needed finessing.

"We've been working on him being able to run off players, to push out to the next man and work for the team (in defence)," Smith said.

His defensive alignment also needed adjusting to fit a rugby backline.

"We want him to keep turning up in defence, you can't do that if you turn in like he was used to doing in rugby league.

"It's been a big work on and the next part of that work on is you've got to get him to finish the tackle off.

"We've got bit of work to do so he actually completes the tackle rather than just keep pushing them (opponents)."

All Blacks head coach Graham Henry was the first speculate on Williams potential as a blindside earlier this year.

And last month Canterbury coach Rob Penney admitted the idea of running Williams there had been discussed midway through the season but it never eventuated.

The All Blacks had their usual light workout to start the week; Joe Rokocoko will make a slow start to training after suffering a knee injury against the English - it is not considered serious.