Baby duties could keep All Blacks fullback Mils Muliaina out of the Hong Kong test against the Wallabies on Saturday week.

Muliaina's wife is expecting the couple's first child and he will stay in New Zealand until the baby is born.

The baby is due this weekend but Muliaina won't be rushing away until it is safely delivered.

Muliaina is a certainty to be in the 35-man tour squad named on Sunday. But he's no certainty to be on the plane to Hong Kong on Monday night.

With fellow test fullback Leon MacDonald out of the frame with his head injury, the All Blacks might have to play with makeshift or rookie cover in the No 15 jersey.

All Black backs coach Wayne Smith said it was questionable whether Muliaina, who has 66 tests to his name and has been super-consistent this season, would make it to Hong Kong in time to be considered for the historic November 1 match.

"Mils has the birth of a baby pretty imminent. We are not sure (if he will be available)," Smith said as Muliaina trained with 25 other members of the All Blacks wider training squad in Auckland on Tuesday.

The All Blacks selectors have had their eyes on Wellington's Cory Jane and Canterbury's Paul Williams as alternatives. They square off in the Air New Zealand Cup final in the capital on Saturday night.

Young Auckland utility Isaia Toeava is another option and he's likely to play fullback at some stage for the training squad in their match with the New Zealand Barbarians in Henderson on Wednesday.

"He prefers centre or fullback. We like what he has done for us aerially this year. He has been good out wider a wee bit," Smith said of Toeava.

"Ice will get some time there tomorrow at fullback and he is certainly an option there for us."