New Zealand centre David Havili is expected to be sidelined for the entire Rugby Championship after suffering a serious hamstring injury in Super Rugby Pacific last weekend.
Havili limped off in the Canterbury Crusaders' home win over the New South Wales Waratahs last weekend and will likely need two months to recover, the Crusaders said.
The All Blacks start their Rugby Championship campaign against Argentina on 8 July.
Crusaders team-mate Cullen Grace [below], a one-Test loose forward, has been ruled out of the rest of the Super Rugby season after suffering a dislocated knee-cap.
"Both are out for the Super campaign, unfortunately," Crusaders coach Scott Robertson told New Zealand media on Thursday of Havili and Grace.
"Really disappointed for them, they're such big contributors to our team and really important parts of it."
With one more regular season round before the play-offs, the second-placed Crusaders have already lost All Blacks props Fletcher Newell, Joe Moody and George Bower, and winger Sevu Reece, for the rest of the campaign.
The defending champions play the Wellington Hurricanes away on Saturday, having already booked their place in the top four to secure home advantage in the quarter-finals.
The Crusaders are looking to stretch their Super Rugby dynasty to a seventh successive year under departing coach Robertson, who will take over the All Blacks after the World Cup in France.
Robertson's eventual successor will face a challenge to regenerate the South Island side who stand to lose a number of champion players after the World Cup.
Former captain and veteran All Blacks lock Sam Whitelock confirmed on Thursday a move to French club Pau where he will reunite with his younger brother and loose forward Luke.
All Blacks fly-half Richie Mo'unga is also leaving the Crusaders to play in Japan next season.
Should Ireland qualify from Pool B in the Rugby World Cup they are likely to face either New Zealand or hosts France in the quarter-finals.