James Mortimer 11.Sep.2012Getty Images
The young Manawatu connection of Aaron Smith and Aaron Cruden were unable to impose themselves in the first half, although the Investec Super Rugby winning first five-eighth came back in the final 40 minutes with a strong performance.
The ferocity of the Pumas defence in tight unsettled much of the play in the close quarters for the opening stanza, and the All Blacks had to scrap to a 6-5 halftime lead.
Hansen said in many respects it was a learning experience for the duo.
"Both our halves are inexperienced from a test point of view," the unbeaten All Blacks coach said.
"You don't always want them playing in games that are easy for them."
"Tonight they were challenged, not so much physically but in a game sense and they will have learned from that. That will have been good for them."
Weepu came on and made a big impact, as did other members of the bench in the form Liam Messam, Andrew Hore and Sam Whitelock.
Hansen said it was crucial that his nine and ten combination take control.
Chiefs playmaker Aaron Cruden will likely don the All Blacks number ten jersey in Dunedin, giving him a full week's buildup unlike his late callup to the team when Daniel Carter tweaked his calf in Wellington.
Smith had a strong season with the Highlanders, and has become the All Blacks incumbent halfback in 2012, but there may be a temptation to play a more 'rugged' nine like Weepu against the physical Springboks.
"Nines and tens, they are the main computers of the team," Hansen said.
"They run the side and move them around the field the way you want them to be moved around.
"We didn't play smart football in the first half. It had a lot to do with the conditions. We tried to play rugby not conducive to the conditions and we were pretty wobbly at times. But late in the first half they started to get things right and we were better in the second half."