The Blues have started looking for a new lock for the 2014 Super Rugby season after it was confirmed that Culum Retallick has been ruled out for the season with a knee injury.
The 28-year-old ruptured his anterior cruciate ligament (ACL) in December and was forced to have surgery last week.
It was hoped Retallick would bounce back to feature towards the end of the season, however the expected recovery time was too long and the Blues have been forced to release him.
"We've taken Culum out of the squad which is a really sad thing to do," head coach Sir John Kirwan said on the Blues site.
"He'll be a big loss for us. The hardest thing about Culum is replacing him because he's a big tall man but he's also got a lot of experience, so when you start looking around to replace those qualities it's pretty difficult," he said.
"We're taking a little bit of time with it and making sure we make the right decisions. We should have a decision by the end of the week."
The Blues have former Highlander and Crusader Tom Donnelly as their leading lock along with Liaki Moli and promising youngster Patrick Tuipulotu as the other second row options.
However Kirwan said he was hoping to replace the 1.98m Retallick with a player similar to his profile.
"It's the experience of Culum that we're concerned about, we don't want to expose some of our younger guys too early if we don't have to and we're looking at middle of the lineout as well.
"We see Patrick and Liaki at the front of the lineout as our hard workers and for middle of the lineout we need someone a bit taller and a bit more competitive from a height point of view so he's quite difficult to replace."
Wider Training Group and Northland lock Tom Murday is an option to be promoted to the full squad, while Auckland Marist lock William Lloyd has been brought in as an apprentice to train with the squad over the last two weeks.