New Zealand's Ma'a Nonu could be ruled out of the Tests against Ireland and Wales in June with a knee injury.
The inside centre, 27, ruptured the posterior cruciate ligament in his left knee playing for the Hurricanes on 14 May but is unlikely to need surgery.
The All Blacks are already without hooker Andrew Hore (shoulder), lock Ali Williams (Achilles) and wing Sitiveni Sivivatu (shoulder).
New Zealand play Ireland on 12 June and then Wales on 19 and 26 June.
It is another blow for coach Graham Henry after 31-year-old Hore, Nonu's Hurricanes team-mate, dislocated his left shoulder in last weekend's Super 14 defeat against the New South Wales Waratahs.
Hore, who started 11 of 14 Tests last year, does not yet know if an operation is required but could be out of action for anywhere between six weeks and six months.
Full-back Mils Muliaina is also recovering from a broken thumb.
Midfielder Nonu was a key figure for the All Blacks last year and started in all but two of the 14 Tests and may also be a doubt for the opening Tri-Nations clash against South Africa in Auckland on 10 July.
Luke McAlister, who started in the 12 shirt when Nonu was rested, has struggled with injury during the Blues' Super 14 season and is not guaranteed to be available for the matches in June.
Stephen Donald is an option at inside centre, while Hurricanes utility and one-Test All Black Tamati Ellison is heading to Japan and is out of contention.
Blues back Stephen Brett, unused as injury cover for the All Blacks last year, could now get his chance when Henry names his 26-man squad at the end of the month.