All Blacks: Conrad Smith heading home

All Blacks centre Conrad Smith has left the squad to return home to New Zealand for what coach Steve Hansen has called a "family matter".

However, Hansen is confident Smith, a recent new father, will return after this weekend's test against Scotland at Murrayfield to be available to play Wales in Cardiff the following week.

"It's not overly serious but it's serious enough for him to have to go home," Hansen said after the squad arrived in Edinburgh today. "Everyone is healthy which is great but obviously it's a personal matter so I can't answer any more questions on it."

Also unavailable for the test against Scotland, who were impressive in beating Argentina 41-31 at Murrayfield on Sunday, is lock Brodie Retallick due to a shoulder problem which forced him from the field during his team's 24-21 victory over England at Twickenham.

Crusader Dominic Bird, who was in England with the Barbarians, has joined the All Blacks as cover, but Hansen thought Retallick would be available to play Wales at the Millennium Stadium.

Experienced midfielder Smith wasn't at his best against England. He was exposed for Johnny May's try in the opening minutes before being replaced by Ryan Crotty early in the second half, but Hansen said he didn't think Smith's personal issue played a part in his performance.

"It just looked like Conrad was struggling a little and we thought Crotts could add something," Hansen said.

"Crotty is playing really well and he came on and did a good job."

Hansen also backed flanker Sam Cane to be available after suffering from back spasms at training late in the week.

The All Blacks coach was happy with the manner of his team's win over England, but said improvements could be made in the connection between the forwards and backs - which was also exposed in the narrow win against Australia in Brisbane - and kicking accuracy.

"This is very much a loseable game so we have to keep our feet on the floor and prepare well as always," he said of the Scotland challenge. "Over the last few years Scotland have managed to beat South Africa and Australia... they have relaxed and allowed Scotland to get into the game and look we all know if you keep someone in the game for long enough they will grow an extra arm and leg and will be very hard to beat."