The All Black Jerome Kaino faces up to two months on the sidelines after suffering a compound fracture to the ring finger of his left hand in Super Rugby action on Saturday.
It was a bad day for All Blacks coach Steve Hansen with Test outside back Charles Piutau and flyhalf Beauden Barrett also suffering knee injuries.
Kaino, who started every match in the World Cup on home soil four years ago and played eight tests for the All Blacks last season, injured the digit during Blues' win over Western Force.
A nominee for World Player of the Year in 2011, Kaino could be sidelined for up to two months, which would rule him out of the rest of the Super Rugby season for the Blues.
"The bone came out of the skin but from what the doctors have been saying it looks a lot worse than what it is," Kaino said.
"Worst case scenario they say eight weeks. Best case scenario I'll be back in a couple of weeks.
Blues coach John Kirwan thought Piutau had suffered a similar medial ligament injury to that which ruled him out for eight weeks last year.
That would be a major blow to the 23-year-old, who had hoped to force his way into Hansen's squad for the World Cup despite his decision to join Irish province Ulster for next season.
Barrett missed the last 10 minutes of the 29-23 victory over the Canterbury Crusaders which kept the Wellington Hurricanes top of the Super Rugby standings but the initial prognosis on his knee injury was better than that for Piutau.
Hurricanes coach Chris Boyd said Barrett, who had tried to play on with strapping around the joint, might be given the second of the mandatory two weekends off that All Blacks must take this season as a precaution.