The All Blacks coaching staff face a sleepless night tonight as they await the results of scans on first-fives Aaron Cruden and Beauden Barrett.

The pair suffered minor injuries in Saturday night's 47-29 victory over Australia in Sydney in the opening test of the Rugby Championship.

Cruden (knee) was summoned to start following a calf injury to Dan Carter, which the 95-test veteran suffered early last week. Then Barrett, who only played the final 10 minutes, picked up a calf problem of his own.

The niggles to Cruden and Barrett have seen Cantabrians Tom Taylor and Colin Slade whistled up to join the All Blacks in Wellington as they build towards the return encounter with Australia at the Cake Tin this Saturday.

Lock Luke Romano was also sent for a scan today to inspect his groin problem, which has seen loose forwards Luke Whitelock and Brad Shields join the squad as cover but it's a potential first-five issue that will have the coaching staff sweating.

"We'll know more tomorrow morning,'' All Blacks assistant Ian Foster said today.

"So I haven't got too many more details to give you about Beaudy, Aaron and Romano but that's the case so we'll know more tomorrow.''

Cruden and Barrett both sat out training this afternoon where Taylor and Slade were both expected to run at five-eighth in a light session.

Foster smiled when asked if an SOS call had been sent to Stephen Donald, who stepped in at the 2011 World Cup after three five-eighths had been knocked out of the tournament with injury.

"No, no. We are happy with what we've got and we've been here before,'' Foster said. "Quite honestly, whilst it's disappointing for the guys that have got niggles it's a great opportunity for the other two and it's going to give us a good chance to get a read on them this week.''

It seemed slightly curious to bring in two loose forwards to cover an injured lock but Foster pointed out they have Jeremy Thrush within their wider training group, while young blindside flanker Steven Luatua also had the ability to cover the second-row.

Midfield back Francis Saili wasn't available for selection last weekend due to an ankle problem but Foster said he was progressing well and could be deemed fit this week.

As part of a new 'apprenticeship' initiative, Highlanders hooker Liam Coltman will train with the All Blacks squad this week.

"I think it's pretty clear the reasons that have lead to it,'' Foster said of the idea. "We've stated that hooker's an area that we do want to develop some young players and I wouldn't call it an academy, I think we'll be loosely using the word `apprenticeship'. It's just a chance to bring a few young players in to give them a taste of what it's like and I guess for us to get to know them a little bit more too.

"So this week it's Liam's turn and hopefully he'll leave the week with a good understanding of what it's like to be an international player and we've got a better knowledge of where he is.''

Foster said Coltman being chosen first was purely down to geography and scheduling and wasn't an indication of the pecking order among the young hookers throughout the country.

A different rake will be chosen to join the squad for the week before the upcoming Rugby Championship tests in Hamilton and Auckland.