Blues head coach John Kirwan is now searching for a second row replacement to come in for the injured Culum Retallick.
The 29-year-old sustained an ACL injury in training last month that has now ruled him out for the Super Rugby season.
Kirwan described replacing Retallick as "really sad", with the lock previously set to play a big role in the Blues' campaign.
"We've taken Culum out of the squad and it was a really sad thing to do,'' Kirwan told the New Zealand Herald.
"He'll be a big loss for us. Today we have to do that official paper work.
"The hardest thing about Culum [going] is replacing him because he's a big, tall man and he's got a lot of experience so when you look around to replace that it's pretty difficult.
"We're taking a little bit of time with it and making sure we get those decisions right. We should have a decision made by the end of the week.''
The loss of Retallick leaves the Blues with the experienced Tom Donnelly in their ranks along with two youngsters in Patrick Tuipulotu and Liaki Moli, but Kirwan was hesitant to involve the latter pair too early, hence the search for a new second row.
"We don't want to expose some of younger guys too early if we don't have to,'' added Kirwan.
"We are looking at the middle of the lineout as well. We see Patrick and Liaki as front of the lineout [jumpers].''
Kirwan also revealed that All Blacks tighthead prop Charlie Faumuina had returned to training to prepare for New Zealand's own pre-season training camp in two weeks time.
"Sometimes it's easier to come in and do the fitness work, and it takes a bit of pressure off you," stated Kirwan.
"It's pretty hard on these guys to train by themselves sometimes, so we're really happy to have them."