HAWTHORN'S key defensive stocks have plunged further into crisis, with midfielder Sam Mitchell confirming on Monday that young big man Jordan Lisle has a fractured cheekbone.

Lisle left the ground during the third quarter of the Hawks' loss to Collingwood on Sunday after a clash of heads with Magpie Leon Davis.

"He's got a depressed fracture of his cheekbone, so he's having surgery tomorrow," Mitchell said on Monday afternoon.

The 20-year-old joins Ryan Schoenmakers, Stephen Gilham and Ben Stratton on the sidelines.

The spate of injuries means Josh Gibson will be Hawthorn's only recognised key defender against the Brisbane Lions and their dangerous captain Jonathan Brown this weekend.

"'Gibbo' has been doing a stellar job for us, he's having a really good season, and he'll continue to do the role that he's been doing," Mitchell said.

"Obviously Jordie will be out for a little while so we'll have to find another defender to fit in there.

"Hopefully (Ryan) Schoenmakers is not too far away and he can slot back into that spot."

Schoenmakers has a sore spot in his foot and was last week listed by the club as two to three weeks away.

Mitchell also addressed concerns over the Hawks' high-possession game plan, which was well countered by the Magpies' outstanding defensive pressure.

He said the team would find areas to improve on from the 41-point defeat, but wouldn't be making major changes.

"The game plan is continually tweaked … every week you go into the game and you learn something new, every week you alter slight things," the in-form midfielder said.

"When you play a side like Collingwood, who defensively are as good as it gets, you learn a little bit more.

"So there are probably a few more things that we need to adjust, but they're very minor.

"The majority of the way we play will stay consistent."

Mitchell said a large disappointment was Collingwood's high number of forward 50 entries.

The Magpies racked up 59 inside 50s to the Hawks' 44, something the 2008 premiership captain hopes to get an opportunity to rectify later in the season.

"We weren't able to stop the flow of the ball going into their front half," Mitchell said.

"That's a strength of their game and we'll learn from that.

"We haven't played them for a while, so we'll figure out how they go about it and hopefully get another crack at them later in the year."

Mitchell expected Michael Osborne (corked thigh), Lance Franklin and Chance Bateman (rolled ankles) and Gibson (black eye) to be fit to face the Lions.

Mark Macgugan writes for hawthornfc.com.au and covers Hawthorn news for afl.com.au. Follow him on Twitter: @mmacgugan.