HAWTHORN could spring a surprise by replacing injured spearhead Jarryd Roughead and retired full-back Brian Lake with smaller running players, coach Alastair Clarkson says.

The Hawks will use tomorrow night's NAB Challenge opener against Carlton as the first test in an experimental phase that Clarkson believes could last until the early rounds of the premiership season.

Roughead, who booted 50 goals last year, will be sidelined for the first half of the season, leaving a major hole in attack that a host of Hawks are eager to fill after biding their time at the club's Box Hill breeding ground.

Strong-marking forward James Sicily is a standout candidate after he bagged five majors in last week's intra-club, while developing tall Tim O'Brien and delisted ex-Demon Jack Fitzpatrick will also push their cases against the Blues.

But Clarkson told AFL.com.au the Hawks are also keen to experiment with a more nimble forward line in the pre-season competition.

"It could be that we don't replace Roughie with a Roughie type, we replace him with a smaller-type player and we go with a more agile and different size of forward line and see if that works for us," Clarkson said.

"It will all be determined by our ability to be able to score and work together in a system.

"So we're going to be on a trial and error basis for the next four weeks in particular as we go through NAB and perhaps the first rounds of the season just to see what that balance is, but we're looking forward to the challenge.

"It's far from great when one of your leading players like Roughie goes down with a serious injury but it does force us to look at different ways of doing things."

In defence, the Hawks might not need another backman capable of standing 'monster' forwards to take over from Lake. 

James Frawley found his niche in a lock-down role in Hawthorn's last three finals and is an obvious choice to take the opposition's star tall forward each week 

But the Hawks still have multiple options, with the versatile Angus Litherland, Kaiden Brand – coming off double shoulder surgery – Kiwi project player Kurt Heatherley, injury-plagued Matt Spangher and youngster Daniel Howe waiting in the wings.

"There's a number of players, like Angus Litherland, who's been at our footy club for a fair period of time and has shown at different stages particularly in the last two years that he can hold down an important role in the back end," Clarkson said.

"If we think Frawley, (Josh) Gibson and (Ben) Stratton are going to take the bigger types then we'll be playing a smaller type of guy.

"At various stages throughout 2015 it was a real challenge playing Gibson, Frawley, Lake and Stratton all in the one side. We were still feeling that as late as the finals series, trying to work out what was our best structure.

"It worked out OK for us, but it wasn't without its headaches throughout the course of the year.

"It's not just because Lakey's gone that we'll just replace him with another Lake prototype."

The Hawks have at least four spots to fill from their 2015 Grand Final team in round one after Lake and David Hale's retirements, Roughead's injury and Matt Suckling's free agency defection to the Western Bulldogs.

Ruckman Jon Ceglar is a near certainty to take over from Hale, while speedy small forward Zac Webster is among the Hawks who should get his chance to impress during the NAB Challenge.

Webster has overcome long-term hamstring injuries by copying Cyril Rioli's revamped training program this summer.

Former No.2 draft pick Jono O'Rourke is also growing in stature at Waverley after a strong pre-season, experienced utility Brendan Whitecross is in top shape and Billy Hartung is determined to secure a regular spot after his Grand Final heartbreak.



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