Scott Barrett is thought to be ruled out of the All Blacks' deciding third test against Ireland in Wellington today.
After starting at lock in the second-test defeat in Dunedin last week, Barrett did not train fully on Tuesday at the Hutt Recreation Ground in Lower Hutt due to what is thought to be a knee injury.
The Crusaders captain was, however, named to start at blindside on Thursday before the All Blacks' main training session of the week where he may have aggravated the injury.
The All Blacks declined to comment on Friday when approached by the Herald about Barrett's fitness.
Blues loose forward Akira Ioane is expected to be promoted to start at blindside and Chiefs lock Tupou Vaa'i, who returned from Covid this week, will come onto the bench to provide cover for Sam Whitelock and Brodie Retallick.
Barrett's withdrawal would be a major blow after he made a notable impact at blindside during the first-test victory at Eden Park, allowing the All Blacks to challenge Ireland's set piece while making 18 tackles.
The performance allayed concerns from fans after Barrett's only previous start in the No 6 jersey, during the All Blacks' semifinal loss to England at the 2019 World Cup.
Barrett's selection for that match backfired but the All Blacks were not beaten solely for that reason, and coach Ian Foster was unconcerned by a single performance.
"He's filled in there a couple of times and played there for the Crusaders. We know he can do it," Foster said before the first test. "I didn't spend too long thinking about the 2019 game. We took some lessons from that but they were learnt a long time ago.
"This one we were very clear about the strategy. It's something we've talked to Scott before about.
"Apart from his set-piece acumen he brings a bruising defence and ball carrying – he's probably our most dynamic ball-carrying lock at the moment so we can utilise that a bit at six.
"He finds the roles similar now apart from a couple of defensive tweaks which we've had to make sure we tidy up."
Barrett's potential absence and the subsequent late reshuffle would only add to the task following the All Blacks' second-test loss.
Although they start warm favourites to win the test and series, the All Blacks have earned victory once from their last five matches in Wellington.