Lock Sam Whitelock is an injury doubt for the second Bledisloe Cup Test against Australia in Auckland, the All Blacks said on Wednesday, while Josh Ioane has been called up as flyhalf cover.
Assistant coach John Plumtree said Whitelock sustained a head knock in Sunday's 16-16 draw against the Wallabies in Wellington and was undergoing concussion tests.
"Sam had some headaches after the game," Plumtree told reporters.
"So we'll work through the concussion protocols and see how he gets on this week. Hopefully he'll be all right for the weekend."
Scott Barrett, who can play at lock, rejoined the squad after a long stint sidelined with foot problems but Plumtree said he may lack match fitness for Sunday's Test at Eden Park.
Ioane was brought in as insurance at No 10, with Beauden Barrett still shaking off an Achilles injury that kept him out of the opening Test and Richie Mo'unga nursing a sore shoulder.
Plumtree said Beauden Barrett's chances of playing appeared promising.
"He's looking likely, absolutely, but he was looking likely this time last week as well... Richie had a little bit of a stinger in the shoulder, but nothing too much," he said.
Teams for the Test at Eden Park, where the All Blacks have not lost for 26 years, will be named on Friday.