"He's only had a really limited amount of game time," Blackadder said today. "With David Havili going back, that's not to say that Izzy will be playing or on the bench. We're going to have a discussion very shortly. It could just be that he's with us and has a full training week with a view to looking at him next week.
"I just want to lower the expectation around him in particular. Ged will be a straight swap, he'll be in the match 23, but with Israel it's more about cover and having a good training week with the team.
"It would be pretty unfair to throw him in the deep end straight in off the bat after not being involved or around the team."
The Crusaders have arrived in Perth from a successful two-match tour of South Africa, where they beat the Sharks and Lions, and they are determined to continue their good form against a team who have presented plenty of problems for them in the past.
Third in the New Zealand conference behind the Chiefs and Highlanders, but having already had their first bye, the Crusaders are looking strong in most facets. Their attack was outstanding at times during their the 43-37 win against the Lions in Johannesburg but the Force will be awkward at home despite a tough recent three-match tour of New Zealand.
"Motivation-wise we've set some high standards and high goals and to perform over here is one of them," Blackadder said.
"History says if we take these guys too lightly or aren't at our very best we can often struggle. [There] was a wee reminder over the weekend about that in the Waratahs [defeat] against the Rebels. Our track record over here has been very average but I don't see that with this team. This is a game in which we will definitely get what we deserve so if we don't front or turn up then it will be one hell of a battle.
"I sense we're up for the challenge because it's been a great two weeks and we just want to keep building our game."