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GEELONG will unleash injury-prone game-breaker Nakia Cockatoo on Friday night in the ultimate game of Russian roulette in a bid to make its first Grand Final since 2011.

Cockatoo and defender Tom Lonergan are the Cats' inclusions in place of omitted pair Zach Guthrie and James Parsons for their preliminary final clash with minor premier Adelaide at Adelaide Oval.

The Crows welcome back Rory Sloane (appendix) and chose a like-for-like replacement for Mitch McGovern (hamstring) in versatile tall Andy Otten. Dashing backman Brodie Smith, who ruptured the ACL in his right knee in the 36-point qualifying final win over Greater Western Sydney, is the other change.

See the full teams here

Cockatoo last played against Carlton in round 19, when he suffered his third hamstring strain in four matches scattered across 71 days. He also hurt his thumb in round one and required an operation.

The 20-year-old lasted fewer than 20 minutes in rounds nine and 13, with coach Chris Scott punting on his huge upside despite the risk of being one player down from early in the contest.

Guthrie, Parsons and Jordan Murdoch, who was dropped after Geelong's 51-point qualifying final loss to Richmond, are the emergencies.

Adelaide named Wayne Milera, Alex Keath and Reilly O'Brien in reserve for the match, which is officially a sell-out.

Richmond and GWS elected to go with unchanged line-ups for Saturday's twilight preliminary final at the MCG.

There was some speculation the Tigers may dump Jason Castagna in response to the small forward kicking just one goal and having a modest 21 disposals across his past four matches.

But Castagna, who has played every game this year after being promoted off the rookie list, will take his place as Richmond strives to win its first premiership since 1980.

Shaun Hampson, Shai Bolton – who was considered the potential replacement for Castagna after sitting out the last quarter in the VFL on Saturday – and Corey Ellis are on standby.

The Giants' major selection dilemma involved former Geelong triple premiership star Steve Johnson's ailing right knee.

Johnson's six-goal second-half haul in last week's 67-point demolition of West Coast showed there was still life in the retiring 34-year-old – and his knee appears to have recovered sufficiently.

That leaves Devon Smith, Sam Reid and Harry Perryman as the emergencies.

Smith, who has been strongly linked to an off-season move to Carlton, lost his spot for GWS's first final because of an ongoing right knee injury that required surgery mid-season.

Friday, September 22

Adelaide v Geelong at the Adelaide Oval, 7.20pm ACST

ADELAIDE

In: A.Otten, R.Sloane

Out: B.Smith (knee), M.McGovern (hamstring)

GEELONG

In: T.Lonergan, N.Cockatoo

Out: J.Parsons (omitted), Z.Guthrie (omitted)

Saturday, September 23

Richmond v Greater Western Sydney at the MCG, 4.45pm AEST

RICHMOND

No change

GREATER WESTERN SYDNEY

No change