Luke Romano's calf injury has forced him to miss the Crusaders' trip to South Africa.
All Blacks lock Romano limped from the field early in the Crusaders' 26-29 defeat to the Hurricanes in Christchurch on Friday and the early international departure the next day meant the team decided to take back-up Jimmy Tupou instead.
The Crusaders, struggling with only two victories from five games - including two home defeats - play the Lions in Johannesburg next weekend and the Cheetahs at Port Elizabeth a week later.
Points are becoming extremely important for Todd Blackadder's team, who are last in the New Zealand conference and 13th overall.
The injury to Romano, a crucial lineout winner and ball carrier for the Crusaders, has compounded his team's woes.