New Zealand first-five Dan Carter may miss up to a month of the Rugby Championship after sustaining a calf injury in a blow for the All Blacks' title defence.
The injured calf will keep Carter out of Saturday night's Bledisloe Cup blockbuster in Sydney, the return clash in Wellington the following weekend and the All Blacks Rugby Championship match with Argentina on September 7.
Carter's absence opens the door for Aaron Cruden or Beauden
Barrett to slot into the playmaker position, but would also force
Hansen to re-consider his midfield options.
Hansen named just two midfield specialists in Ma'a Nonu and Conrad Smith in his 28-man squad, and had expected Carter to provide injury cover at inside centre.
"It will give us plenty of food for thought over the next 24 hours," Hansen told reporters in Porirua, near Wellington.
"It does make us think who will cover 12 (inside centre) so we will have a bit of thought on that before we name the team on Thursday."
The 31-year-old Carter is expected to be sidelined for three to four weeks.
"He was a bit sore after training so we got a scan and unfortunately he's damaged his calf," Hansen told reporters in Porirua, near Wellington.
"It's disappointing for Dan ... It's not a biggie. It's just something that is a nuisance more than anything else."
The strain in Carter's left calf was a recurrence of an old
injury, Hansen added.
Carter has had a number of leg injuries in recent years, and
announced last week that he would take a six-month sabbatical from
rugby after the All Blacks' northern hemisphere tour in November in
the hope of prolonging his playing career up to the 2015 World
Carter's decision was influenced by his 32-year-old captain Richie McCaw, who recently returned to rugby refreshed after a similar sabbatical.
"It's a bit frustrating especially when the body was feeling good," said Carter, who had no idea how he had sustained the injury. "I've had injuries like this before so I know what I have to do to get back playing again.
"It's the first time I've done a calf this year so it's important that I just do the rehab so it doesn't happen again this year."
Hansen said Carter's planned break from rugby was unlikely to come at a better time.
"It really reiterates why he needs to have this extended break and get all the little niggles dead right so he can come back and play on a consistent basis," Hansen added.
"That's the nature of the beast, though. Rugby is a contact sport and DC will go away and work on what he has to do to come back."
- With Reuters