THE ABSENCE of Dan McStay for Saturday's semi-final against the Western Bulldogs leaves Brisbane with a giant-sized selection headache that could define its season.

McStay is not a household name, but the inadvertent knee from Nakia Cockatoo that knocked him out in the opening five minutes against Melbourne on Saturday night, again highlighted his value.

Already missing Eric Hipwood with a season-ending knee injury, McStay's bloodied face and concussion left Brisbane exposed in the air, both inside forward 50 and around the ground.

The 26-year-old is Brisbane's best contested marking forward, ranked seventh in the competition among key forwards in that statistic.

In his absence, the Lions were left to rely on the often double-teamed Joe Daniher, inexperienced Tom Fullarton and makeshift forward Jarrod Berry as key targets. Not surprisingly, they had little impact against the best defence in the competition with service from a midfield that was having its colours lowered.

Brisbane had a 14-4 record with McStay in its team before Saturday night, but will be without him this weekend.

There is no ready-made replacement to step in, meaning Chris Fagan and his match committee have a number of less-than-perfect options to explore.

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Brisbane hates tinkering with its structure of three tall forwards, so this would be one of its preferred options. However, the only uninjured tall player left on its list that has spent any significant time as a forward is 22-year-old Connor Ballenden. There's two things to consider there, though. Firstly, it would pair three-gamer Ballenden alongside 13-gamer Fullarton - two green, inexperienced options that are not yet proven at the highest level. Secondly, and just as pertinent, Ballenden has played as a key defender in the VFL all season.

Bring in Archie

This one is slightly left field. Back-up ruckman Archie Smith has played just 16 AFL games, but the 26-year-old is fit and raring to go against whoever the Bulldogs throw up, including one of his former mentors Stefan Martin if he's selected. Smith's inclusion would then push Oscar McInerney – who has been the Lions' No.1 ruck all season – to the forward line. 'Big O' cut his teeth as a forward, spending the majority of his first 50 games alongside Hipwood and McStay in the forward 50 as an understudy to Martin. Like anyone not playing regular senior footy, Smith has been starved of opportunities in the COVID-affected VFL season, but played in a scratch match against Southport on Sunday and is available.

Go small

Not without a chance, although this is the least likely option the Lions will take. Fagan has shown he loves to stick with three tall options, regardless of the circumstances. If the Lions can't immediately attack, they're happy to kick long along the boundary line to an aerial contest, or long to the forward pocket to a contest where they hope a tall will either mark or bring the ball to ground and force a stoppage. However, the option to go with Daniher and Fullarton and surround them with smalls is not silly. Callum Ah Chee (groin) is questionable to return from injury, while Tom Berry or even Deven Robertson could act as small forward terriers while either Nakia Cockatoo or Linc McCarthy played as a pseudo third tall.

Shuffle the magnets

Perhaps the answer is already in the team and just needs a shuffle of players. Marcus Adams has previously played forward as a Bulldog and spent time there for a couple of games early in his Lions career in 2019. He's aggressive, physical, and as we've seen with his superb defensive efforts this year, rarely gets out-marked. In terms of 'playing a role' Adams seems ideal, although it would be a case of robbing Peter to pay Paul from a backline battling with some niggles. Jack Payne, standing 197cm, could come in to fill the void in the back half left by Adams against Tim English or Josh Schache, while Ryan Lester will slot in after missing a week with a hamstring strain.

There's no perfect answer, but Fagan and his match committee have options they need to mull through to ensure there's not a repeat of Saturday night's patchy work going forward against the Bulldogs.