CARLTON will take a smaller forward line into this Friday night's semi-final against Melbourne, with Jack Silvagni deemed "not ready" for senior football despite passing a fitness test earlier this week.

The Blues need replacements for former Coleman Medal winner Harry McKay (concussion) and the in-form Jack Martin (suspension), with hardened midfielder Matt Kennedy now looming as a likely inclusion.

Kennedy, at 188cm, has shown his wares as a marking option in recent seasons and appears destined to join small forward Jesse Motlop in a more dynamic Carlton side on Friday evening.

That's despite Silvagni passing a fitness test on a knee sprain injury on Wednesday, with Blues coach Michael Voss saying it was a case of whether he was ready for senior football following seven weeks out of the team.

"He got through," Voss said.

"He's certainly available to play. I guess the question we have to ask is if he's ready. He'd be coming in without having played a game first, so we have to weigh that up as a match committee. We're weighing up availability against ready-to-play."

Silvagni was not among the 26-man Carlton group training at Ikon Park on Thursday, with the Blues later saying the free agent forward would be available to play VFL football if their affiliate side was still alive in reserves competition.

However, with Silvagni set to miss out on finals action, Carlton is poised to take a smaller look featuring Kennedy and Motlop at the feet of its back-to-back Coleman Medal winning forward Charlie Curnow against Melbourne.

"What we've been able to find is some real cohesiveness with our group," Voss said.

"We've been able to play taller, and that's certainly worked for us. We've gone with a bit of a smaller look, which has proved to be successful as well. We'll weigh up what the roles we need.

"Clearly, having an aerial presence is going to be pretty important. There are obviously a couple of (Melbourne) players that go well in the intercept game, they defend as well as any team in the competition.

"It'll be a tightly fought match and we'll have to take those opportunities when we can. "Certainly, our boys are going to have to compete in the air and get the ball to ground. We're weighing all of that up and what we need to make that happen."