Damian McKenzie has been brought into the All Blacks squad amid concerns for fullback Ben Smith who was forced off with concussion in the first-Test win over the British and Irish Lions.
Smith left the field in the first half of the 30-15 victory at Eden Park on Saturday after making some uncharacteristic errors under the high ball.
He failed a concussion check.
It is Smith's third concussion this season and All Blacks coach Steve Hansen said the vice captain's run of head injuries was a concern.
"Benda (Smith) failed the concussion tests so he is undergoing protocols and Damian McKenzie will come in for him," Hansen told reporters on Sunday.
"There's something going on there that is not quite right, so we need to find out what it is.
"Like any concussion, he's got to go through the protocols and until he passes them he's not going to play.
"He still has to (undergo) testing. It's not something we will rush into. We will give him a few days and let him go through it."
Centre Ryan Crotty also injured his hamstring in the first half on Saturday and could be out for anything from two to four weeks, Hansen said.
Crotty's Crusaders' Super Rugby teammate Jack Goodhue, who was one of five additional players named with the All Blacks squad as injury cover, would remain with the team.
Flanker Matt Todd, another of the cover players, was released after he sustained a calf injury during training.
Hansen released fullback Jordie Barrett, inside centre Ngani Laumape, winger Julian Savea and flanker Vaea Fifita to play for the Hurricanes for their match against the Lions on Tuesday.