An elbow injury to explosive centre George Moala adds another level of uncertainty to the All Blacks squad makeup to contest the Rugby Championship.

Moala stretched elbow ligaments which forced him off early in the second half of New Zealand's 46-6 demolition of Wales in Dunedin on Saturday.

It ended a hugely impressive display in just his second Test and is likely to sideline the 25-year-old for three to four weeks.

Blues prop Charlie Faumuina could miss anything from one to three weeks after damaging knee medial ligaments.

With the Blues unlikely to reach the Super Rugby play-offs, it may be the end of the pair's Super Rugby campaigns.

Moala will thus have few chances to push his claims as coach Steve Hansen assesses a logjam of midfield candidates for the Rugby Championship.

Sonny Bill Williams is poised to return following a probable Olympic sevens campaign, although Hansen confirmed the code-hopper won't be available for the opening Test against Australia in Sydney on August 20.

Malakai Fekitoa, Ryan Crotty, Moala and Seta Tamanivalu all had their moments during the three-Test sweep of Wales while Hansen is keen to field the injured Charlie Ngatai as soon as possible.

Crotty suffered a calf injury early in the Dunedin Test which has him in doubt for the Crusaders' clash with the Chiefs in Suva next week.

Hansen indicated Crotty will fill one of probably four midfield spots in his 32-man squad named in early August, comparing him to departed great Conrad Smith.

"Ryan's never played poorly for the All Blacks. He's not your big x-factor game-breaker but he always does the right thing at the right time," he said.

"He's a little like Conrad. The more he gets confidence in being out there, the more he'll command a presence."

The other contentious area is the back three, where fullback Israel Dagg has virtually bulldozed his way back into the starting team.

Dagg has shone in his two Tests since being omitted from last year's World Cup. Regular breaking on counter-attack, his 196 running metres in Dunedin was more than the combined Welsh team could manage.

World Cup fullback Ben Smith stood out on the right wing, while Hansen has two bullocking wings at his disposal in Julian Savea and Waisake Naholo.

"We're going to have to make some massive choices when they're all playing well," Hansen said.

"On his form at the moment, it's going to be very difficult to leave (Dagg) out.

"Ben's form, no matter where you play him, he's just such a good footy player. Both of them will be there somewhere."

Another conundrum is the role of regular impact bench player Beauden Barrett, who thrived in a rare start at first five-eighth in place of the injured Aaron Cruden.

Barrett scored two tries in a 26-point haul, the most by any All Black since Dan Carter's 27 against the Welsh in Cardiff six years ago.