All Blacks loose forwards Kieran Read and Sam Cane have been ruled out of the New Zealand team to play the first Test match against England this weekend.
Read has been ruled out of the opening test due to ongoing concerns over concussion-like symptoms which kept him out of Super Rugby for six weeks.
Meanwhile Sam Cane has been ruled out of the three Test series with a knee injury.
There is also a doubt over winger Julian Savea who has a long-standing knee injury that will require a scan later on Tuesday.
2013 IRB Player of the year Read said his symptoms made him feel like he was in 'a fog' especially after physical exertion.
Read initially suffered the knock playing for the Crusaders against the Chiefs in April and returned to Super Rugby last weekend.
Hansen says that Read had woken up on Monday "not feeling well" and the decision was made to withdraw him from the match.
"We're not prepared to risk him playing and that's our decision, not his, and we'll progress that day by day," Hansen told Fairfax.
"He's frustrated, as you would be, but we're very lucky we've got capable people who can fill in his place. Jerome Kaino and Victor (Vito) have been performing very well and Liam (Messam) is an incumbent.
"We've got some good people to step up."
Twenty-eight-year-old Read has been replaced in the squad by Steven Luatua but he is unlikely to start as Jerome Kaino or Victor Vito are expected to start in Read's absence.
Cane has been replaced by Crusaders' Matt Todd, who has not played for a month due to a calf injury.