Blues coach John Kirwan is on the hunt for a new lock after being forced to release the injured Culum Retallick.
Retallick, 29, damaged the anterior cruciate ligament in his right knee during training four weeks ago, with Kirwan revealing today that the 1.98m second rower's season is over.
"We've taken Culum out of the squad and it was a really sad thing to do,'' Kirwan said.
"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.''
Tom Donnelly, 32, who has played for the Highlanders and Crusaders, will begin his first season at the Blues ranked as their No1 lock.
The only other specialist second rowers at the Blues are Liaki Moli and Patrick Tuipulotu.
The latter, a New Zealand under-20s representative, turns 21 in a fortnight. All Black loose forward Steven Luatua is a possibility to play at lock but Kirwan is unlikely to want to limit his impact with a role in the tight.
"We don't want to expose some of younger guys too early if we don't have to,'' Kirwan said. "We are looking at the middle of the lineout as well. We see Patrick and Liaki as front of the lineout [jumpers].''
The Blues play the first of their three pre-season matches against the Hurricanes in Masterton on February 1. They also play the Waratahs in Sydney and Chiefs in Rotorua. Their first competition game is against the Highlanders in Dunedin on February 22.