Hansen admits All Blacks are taking a gamble, awaiting Sonny Bill Williams return

All Blacks coach Steve Hansen has admitted he has taken a gamble in making so many changes to his team for the third test against Wales.

As he said, making 12 alterations to the match-day squad of 23 - including five in the starting line-up - is about "risk and reward", and that risk must be considered highest in the midfield, where he has selected George Moala for his second test alongside Ryan Crotty, who is playing in his 18th.

That combination by itself shouldn't concern All Blacks supporters unduly. Moala is a damaging runner and defender and Crotty a reliable operator in the No12 jersey, but an added throw of the dice is the fact that outside back Waisake Naholo, on the reserves bench after starting the first two tests on either wing, will cover centre.

Seta Tamanivalu, pressed into action from the bench early for Malakai Fekitoa at the Cake Tin last weekend, does not feature, with Fekitoa given a rest after suffering a deep cut to his head and a bang on the knee after his collision with 110kg No12 Jamie Roberts.

The search for a midfield solution has been forced on Hansen by the departures of Ma'a Nonu and Conrad Smith, plus the sevens duties of Sonny Bill Williams and Charlie Ngatai's concussion, but an early injury to Moala could see the All Blacks compromised.

Naholo had a rollercoaster of a test at Eden Park, and while he was steadier at the Cake Tin, an early entrance into the midfield would be challenging.

"We don't have too many options because Mala's injured," Hansen said. "We could have put him out there if it was a life or death situation but it's not. He's got a pretty nasty cut and a leg injury and he's still got plenty of rugby to play for the Highlanders.

"We could have used Bender [Ben Smith] in the midfield [as cover], but you're asking a guy to cover fullback and wing so he's got enough on his plate - plus being vice-captain.

"Wise [Naholo] has played a lot of rugby at centre, he played there a lot at school and when we talked to him about it he was comfortable and he has looked comfortable training there this week."

Hansen confirmed that Williams will be brought back straight into the Rugby Championship squad for the Bledisloe Cup test against Australia in Sydney on August 20, fitness permitting.

With Ngatai presumably recovered by then (and he is now exercising headache-free, according to Hansen), there is likely to be casualties in terms of the current midfield.

However, the selectors may decide not to include first-five or fullback "project" Damian McKenzie in that squad, which could mean that either Moala or Tamanivalu could drop out.

Asked why Tamanivula wouldn't feature on the bench in Dunedin - with the backs reserves made up of Tawera Kerr-Barlow, Lima Sopoaga and Naholo - Hansen said: "We need to find out about some of these guys. We've got Sonny coming back after the sevens so obviously one of this group has to go."

After a difficult start to the Super Rugby season with the Blues, Moala, in and out of Tana Umaga's side, has been steadier recently, and his work and form in training while with the All Blacks has convinced Hansen he is ready to go.

"It's taken Tana a wee while to get him to relax and play with confidence," Hansen said.

"The latter part of Super Rugby he started to do that and we started to see the George of old, he's a strong ball carrier and he's punishing on defence. While he's been with us he's worked incredibly hard and we just feel that deserves a reward."

Blues teammate Charlie Faumuina, starting at tighthead prop on Saturday, said of Moala's power: "It's probably the reason why he's George of the Jungle in the gym. He's pretty strong mate, he's not someone you want to be marking when he runs straight at you."