Nevertheless, France were playing good rugby and would be a force to be reckoned with.
Interviewed in the run-up to the quarter-finals, Sir Brian said the All Blacks, of which he was once captain, coach and selector, were "trucking okay" despite some lapses in pool play.
"The worst feature has been the lack of accuracy with passing and catching but the players, more than anyone, know they have to get better at that."
Apart from 40 minutes or so against Argentina, the All Blacks had not been put under pressure and in the play-offs, the team could be expected to move into top gear, with some new moves in their repertoire.
Sir Brian said the squad would be taking each game as it came and concentrating on executing the game plan, match-by-match.
"That's the only way to win a World Cup."
Apart from France, the teams he most feared might take the cup from the All Blacks' grasp would be the old foe South Africa or Australia, although Ireland and Argentina could not be counted out.
Japan was another nation much better organised this time round and "improving all the time".
Sir Brian doubted the early departure of host nation England would impact on the success of the tournament.
"The grounds are sold out and you can't tell me people who might have paid $1200 for a seat are not going to go," he said.
" If they don't go, they would have to try and sell their tickets; the organisers have already been paid."
He felt for England's coach, Stuart Lancaster, whom he described as "a hell of a good fellow" who had changed the culture of English rugby.
Likewise, Warren Gatland was "clearly a good coach" who had improved the Welsh team and "I really rate Joe Schmidt".
As far as individual All Blacks were concerned, Sir Brian said the team management should be feeling pretty pleased with wing Nehe Milner-Skudder and loose forwards Victor Vito and Sam Cane.
Apart from other attributes, Vito had proved he was a handy lineout jumper and Cane was a player of the future.
"From all accounts, he (Cane) is a top man and the management must have faith in him to have made him captain for one of the games," Sir Brian said.
He was not so pleased with the scrum laws and the persistent use of the television match official (TMO).
'Scrums are supposed to be a way of starting play not to simply try to milk a penalty. I cringe every time I see that happen. It drives me spare at the time it takes these days to put down a scrum, it's a blight on the game."
The TMO should never be the number one decider, in his opinion.
"You have two international referees working the sidelines and an international referee adjudicating the match on the field. The TMO should be rated number four, not number one," he said.
His playing days and coaching stints over, Sir Brian remains a lover and a critic of the game, "like all New Zealanders", and has the honour of being New Zealand Rugby Union patron.
