So was Dagg ready to step up for such an important match?
"His form would suggest he is, that's what you pick players on," Hansen said.
"He has been in outstanding form and risen to the occasion every time he has played for the All Blacks. I don't think he has had a poor test match. He is an effervescent young man who believes in himself so if he gets a chance it will be exciting."
Dagg began his first two tests and the last two of his eight internationals at fullback.
The word on Daniel Carter was encouraging. His back complaint had eased and he was ready to resume after Colin Slade filled in against Japan.
"Carter is ready to go, great news isn't it, great for the tournament, great for him and great for us," Hansen said. "He is a great player and you want your great players, in all the sides, to be available to play."
Hansen was then asked if Carter had been fit to play in the quarter-final loss to France at the last World Cup.
Hansen did not want to use that as any excuse for the All Blacks or Carter on that night four years ago in Cardiff. The first five-eighths had been picked to play and many players who had niggles were involved in test rugby, Hansen said.
The halfback selection merry-go-round continues but Weepu will figure somewhere, even if it is as a backup halfback and first five-eighths. The All Black panel likes him in that role.
That did not mean, Hansen said, that Weepu was the best backup first five-eighths; Slade was the selectors' preferred deputy but picking Weepu gave them greater selection flexibility.
ALL BLACKS (probable)
Israel Dagg
Cory Jane
Conrad Smith
Ma'a Nonu
Richard Kahui
Daniel Carter
Jimmy Cowan
Adam Thomson
Richie McCaw (c)
Jerome Kaino
Brad Thorn
Sam Whitelock
Owen Franks
Keven Mealamu
Tony Woodcock
Reserves: Andrew Hore, Ben Franks, Ali Williams, Victor Vito, Piri Weepu, Sonny Bill Williams, Mils Muliaina.by Wynne Gray