New Zealand centre Jordie Barrett has been ruled out of the second test against Australia in Wellington with a knee injury, the All Blacks said on Tuesday.
He will miss Saturday's return match against the Wallabies in The Rugby Championship after limping off at halftime in Sydney last weekend before the All Blacks clinched a 31-28 victory over Australia to retain the Bledisloe Cup.
Barrett, one of three brothers in the All Blacks squad, flew back to New Zealand with the team wearing a knee brace.
The injury throws a question mark over whether the 27-year-old will be fit for New Zealand's tour of Japan and Europe, starting late October.
"Jordie Barrett's injury is confirmed as a medial collateral ligament. He is out for this weekend and will be reassessed before the northern tour," said the All Blacks media manager.
Uncapped Crusaders back Chay Fihaki has joined the squad as injury cover. The All Blacks face Japan in Yokohama on October 26, before playing England, Ireland, France and Italy on their end of season tour.
Barrett is set to join Irish side Leinster at the end of the year as part of a six-month sabbatical from his current New Zealand Rugby contract, which runs until 2028.
New Zealand cannot retain The Rugby Championship title having already lost twice away to current leaders South Africa this season, as well as suffering a shock home defeat to Argentina in Wellington.
The All Blacks sit third in the table with Australia bottom after a single win over Argentina and four defeats.