The Geelong pair was upgraded on Tuesday, given long-term injuries to Josh Cowan, Dawson Simpson and Lincoln McCarthy.
The Cats' ruck stocks have been decimated by injury, with Hamish McIntosh, Nathan Vardy and Trent West all having interrupted pre-seasons.
West is touch and go for the season opener, with the elevations suggesting the Cats may be cautious with the ruckman's return.
If selected, Walker would play just his eighth game of senior football, while Blicavs would be making a surprise debut against the Hawks.
Blicavs was not even training with the Cats this time last year as he attempted to make the Australian team for the London Olympic Games in the steeplechase.
Blicavs, who turns 22 on Thursday, was selected by Geelong as a category B rookie in the 2012 NAB AFL Rookie Draft, having not played football since the under-14s.
Walker managed seven games after making his debut in round 16 against Collingwood last year.
Both have shown they are capable of handling the ruck load throughout the NAB Cup, facing the likes of Adelaide ruckman Sam Jacobs and Collingwood's Darren Jolly.
Blicavs, in particular, has received glowing endorsements from teammates and coach Chris Scott.
"I'm not one for massive statements, but to answer the question, 'What's his running power like?' there's never been a 198cm AFL footballer who can run like him," Scott said recently.
Walker said he aimed to earn a permanent spot in the Geelong side.
"I exceeded all of my expectations last year," Walker told geelongcats.com.au.
"I was rapt to play as many games as I did and hold my spot in the team.
"I've had a taste of what it's like at AFL level and now I want to cement myself in the team as soon as I possibly can."
Mark Blicavs is a $108,500 midfielder/ruckman in AFL Fantasy and Josh Walker is a $221,500 forward in AFL Fantasy. Register your team at our AFL Fantasy hub.
Ben Guthrie is a reporter for AFL.com.au. Follow him on Twitter @AFL_BenGuthrie
