Portion control and a razor have helped Brandon Starcevich slim down for Brisbane's premiership push.

But the defender knows he might have a bit more on his plate now that they're without a key ingredient of the Lions' back six.

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Keidean Coleman will miss the rest of the season after rupturing his anterior cruciate ligament (ACL) in last Friday's loss to Carlton.

The 23-year-old had emerged as one of the AFL's most incisive kicks out of defence and his absence will hit last season's grand finalists hard.

"It's going to be tough; Kiddy's become a very important player for us in the last couple of years," Starcevich said of Coleman ahead of Sunday's clash with Fremantle.

"He can really tear apart defences and kickstart our movement.

"It'll take all of us to bridge the load."

The imminent return of Conor McKenna (hamstring) and arrival of Adelaide key defender Tom Doedee means the Lions aren't without options.

Dayne Zorko, Jarrod Berry, Cal Ah Chee and even Cameron Rayner have also spent time in the back six.

Either way it likely means a tactical shift for Starcevich, who has primarily served as a lock-down defender but may now be asked to push the tempo.

"I try and do a bit of both anyway, but might have to try and switch my focus a bit more," Starcevich, sporting a shaved head since late last year, said.

"I'll try and get involved as much as I can."

The 24-year-old placed an emphasis on his diet in the off-season in an effort to trim down.

"Just feeling better moving around; moving better and still feeling strong," he said of his motivations.

"Just a little shift in diet stuff, a bit more diligent and focused on that.

"Nothing obscure, just watching how much I ate."

He said Doedee, who is mere weeks away from a comeback from his own ACL tear, had slotted in seamlessly and applied selection pressure.

"It puts the pressure on you to perform and hopefully you're not the guy that misses out," Stacevich said.

"His best is really good.

"A character like Tom ... a really smart footballer who can slot in easily."

Perth native Starcevich said his mother had requested "30 or 40" tickets to Sunday's clash with the Dockers, who will be playing their first game of the season.

"It's a good trip to have, to Perth against a Freo team building," he said.

"They've been preparing all summer for this one, we had our eye on last week."

He said Monday's review of the one-point loss to the Blues was lengthy but not demoralising.

"Watching both parts of the game; what we did really well and the 25 minutes that wasn't so good," he said.

"It's good for those things to happen in March and learn from it."