Roberts, at 6ft 4in tall and almost 17 stone, has emerged during the past year among the most destructive centres in world rugby.

And New Zealand skipper McCaw saw enough of this summer’s British and Irish Lions tour to realise just how influential 22-year-old Roberts can be in the rarefied Test match atmosphere.

“He had a great tour with the Lions,” said McCaw. “He gave them a lot of go-forward against the Springboks.

“He’s a big man, and someone we will keep an eye on. He was a major part of why the Lions played as well as they did in South Africa.

“I was really impressed by the Lions and was surprised how well they played. They could have won the series.

“They played a pretty good brand of rugby and put the Springboks under a lot of pressure. The Welsh players had quite an influence on that.

“Wales have good players, and we realise we are in for a tough match on Saturday. We would be idiots if we thought it was going to be easy.”

New Zealand arrived in Cardiff following a poor Tri-Nations campaign by their standards, losing three games - all to South Africa - and finishing a distant eight points behind the world champions in the final table.

But their record against Wales shows an unbeaten run since 1953, an overwhelming sequence of victories that includes five at the Millennium Stadium, approaching an average of 37 points a time.

McCaw, who leads New Zealand for the 41st time on his 78th Test appearance, will aim to do what he nearly always does and boss the critical breakdown area.

But Wales also possess a magnificent number seven in 88 times-capped Martyn Williams, and their intriguing head-to-head could go some way towards deciding the contest.

“I’ve got a lot of respect for Martyn,” said McCaw. “He’s played a lot of Test match rugby - he has been around a long time.

“The games I have played against him have been a good challenge.

“He plays with style and is a very good link-man. He is also good in defence, serving the team very well.”

The All Blacks continued their preparations in Cardiff today, with head coach Graham Henry having announced a team showing six changes following last Saturday’s win against Australia in Tokyo.

Stephen Donald will move off the bench to replace Dan Carter if the superstar fly-half is ruled out with calf muscle haematoma.

Henry’s line-up also includes one new cap in 20-year-old Wellington Hurricanes wing Zac Guildford.