Jacob Weitering at Carlton training on September 18, 2023. Picture: AFL Photos

MICHAEL Voss concedes Jacob Weitering is "unlikely" to be fit for the start of Carlton's season as the gun key defender faces an important period in his recovery from a significant calf injury.

The star backman suffered a high-grade calf strain at training in January that was expected to sideline him for six-to-eight weeks of the pre-season. 

With Carlton's campaign beginning in Opening Round against Brisbane on March 8, coach Voss said it was likely the 26-year-old would be unavailable to face the Grand Finalists at the Gabba.

"I think it's unlikely. He's on that edge about whether he does or he doesn't, but certainly in the next week or two he has a couple of milestones he needs to tick off for him to feel comfortable," Voss told AFL.com.au.

"I'll wait for those milestones and make some definitive calls on when we think [his return date] might be."

The Blues then face Richmond the following week in round one before they have a bye in round two.

Weitering is the Blues' major injury concern ahead of the season starting, with Jack Silvagni ruled out for the year after going down with an ACL knee injury at training last month. It was a similar story for Zac Williams last off-season, with Voss and the Blues ready to welcome back the dashing defender to their backline.

Zac Williams during Carlton's match against Collingwood in round 23, 2022. Picture: AFL Photos

Voss said the former Giant was ready to return after looking set for a strong season in 2023 before the injury struck.

"It was so unfortunate last year when he was flying through pre-season," he said. "He brings a lot of natural energy to our group and he's clearly a very good player. We missed him a lot last year and having him back is going to be fantastic."

In breaking its 10-year finals drought last season on the way to the preliminary final, Carlton bolstered its list in the off-season with two rival recruits – Gold Coast's Elijah Hollands and former Bomber and Power forward Orazio Fantasia. Voss volunteered Hollands, the older brother of Blues midfielder Ollie, as being a pre-season standout at Ikon Park.

"He's had a really strong pre-season. I was a little familiar with him but didn’t know him as well as (list manager) Nick Austin did and Nick led the charge with our recruiting team on that one and certainly his pre-season has been really strong and he's put his head down and worked his butt off," he said.

Fantasia didn't play at AFL level last season and managed 19 games in three years with the Power as he battled injury, with Voss, who coached him while he was at Port Adelaide as an assistant, saying the Blues had managed his training program.

"We tend to use the magic number of about 80 per cent when it comes to pre-season completed and he's been able to do that. We've been able to build him a little bit slower than some of the other guys. We're very bullish on what he can do," he said.

"I was in the fortunate position where I knew him beforehand. There's still some probably serious question marks around his body and whether he's going to get there, which is fair enough, but everything he's done for us has been really impressive and he's been a true pro. He's settled into the group like he's been here three or four years but that's probably the value of being able to bring in a bit of experience."

Orazio Fantasia at Carlton training on November 27, 2023. Picture: AFL Photos

Voss has preferred stability over experimentation during the summer, with the Blues focused on building up their players' strengths rather than trialling them in different positions. Ollie Hollands has spent more time playing as an inside midfielder after his excellent debut season on the wing, and the Blues will toy with using Harry McKay more in the ruck at times, but Voss has otherwise focused on continuing to build the chemistry of his side after last year's deep run into September.

"I've tended to have just gone with the [view of] 'let's get stable, let's build our cohesion and time together'. You'll see subtleties in differences. Our roles last year were pretty defined and we'll see a little bit more flexibility in that," he said.