- Jackson Trengove among three Power players dropped

- Melbourne axes defenders Christian Salem and Sam Frost

- Dogs get back three flag winners; Greene, Patton in for GWS

PORT Adelaide has responded savagely to its dismal Showdown effort, dumping three players – with the potential for more – ahead of Sunday's clash with Collingwood.

Versatile tall Jackson Trengove is the biggest name of the dropped trio, joining Aaron Young and ex-Bomber Angus Monfries on the outer. Defender Jack Hombsch (hip) will also miss.

Chad Wingard, after two weeks out with an ankle issue, Dan Houston, Matt White, Brendon Ah Chee, Jake Neade, Dougal Howard and Riley Bonner are the Power ins. Wingard, Houston and Howard are confirmed in the side.

The Magpies were forced to make three changes, with oft-injured Daniel Wells (quad), Levi Greenwood (knee) and Brodie Grundy (suspension) out.

Check out the full round 21 teams

Josh Daicos is in line to make his much-anticipated debut, among the five ins with Tim Broomhead, Josh Smith, James Aish, Mason Cox and Callum Brown, although he is named on the extended bench. Cox and Brown are confirmed starters.

In other news, Melbourne has swung the axe on defenders Sam Frost and Christian Salem for its must-win battle with St Kilda at the MCG on Sunday.

The Demons could pick midfielder Angus Brayshaw for his first game since round two after repeat concussions. Josh Wagner, Billy Stretch, Sam Weideman are the other potential additions, with Mitch Hannan guaranteed a start.

Their opponent, St Kilda, will be without the soon-to-retire Nick Riewoldt (concussion), but could bring back Sam Gilbert, Tom Hickey, Daniel McKenzie and Jack Lonie, all of whom are named on the extended bench.

Greater Western Sydney welcomes back stars Toby Greene and Jonathon Patton as its top-two placing goes on the line against the Western Bulldogs at Etihad Stadium on Friday night.

Patton could form a makeshift ruck combination with Rory Lobb, with the Giants overlooking Dawson Simpson, who impressed in his one game a fortnight ago, in Shane Mumford's suspension absence. Small forward Devon Smith (knee) is also out.

The Bulldogs regain a big name, too, in 2015 All Australian Jake Stringer, who will play his first match in a month after a hamstring injury.

Fellow premiership players Tory Dickson and Josh Dunkley also return in place of Easton Wood (hamstring) and omitted pair Clay Smith and Lukas Webb. Jason Johannisen will miss again after he was a late withdrawal last week with a hamstring issue.

Sydney is backing in the group that upended Geelong a week ago, with skipper Josh Kennedy (hamstring) missing for a second straight week as his Swans host Fremantle at the SCG on Saturday.

The Dockers promoted impressive young ruckman Sean Darcy as well as Matt Taberner and Josh Deluca for Jonathon Griffin (omitted), Hayden Crozier (concussion) and Brady Grey (hamstring).

Brownlow medallist Patrick Dangerfield headlines Geelong's inclusions for its top-four showdown with Richmond at Simonds Stadium on Saturday.

Daniel Menzel, Steven Motlop and Rhys Stanley are also set to bolster the Cats, who lose captain Joel Selwood (ankle) and Tom Hawkins and Mitch Duncan (both suspension). Wylie Buzza was dropped.

Jack Riewoldt will return for in-form Richmond at Anthony Miles' expense, after missing two matches with a nasty eye injury.

Gold Coast's interim coach Dean Solomon will be without his two biggest stars – Gary Ablett (hamstring) and Tom Lynch (knee) – in the QClash with the Brisbane Lions at the Gabba on Saturday.

But the Suns' post-Rodney Eade era will start with David Swallow, Jarryd Lyons, Callum Ah Chee and Ben Ainsworth in the line-up. Recycled duo Jarrad Grant and Mitch Hallahan made way.

Chris Fagan's Lions have lost patience with out-of-form forward Josh Schache, sending him back to the NEAFL after kicking one goal across his past three outings.

NAB AFL Rising Star nominee Alex Witherden's promising start to his career is temporarily on pause, with a hamstring injury costing him his spot. Michael Close and Sam Mayes replace them.

Essendon will rely on a mix of veterans and youth to shake up its line-up ahead of a season-defining match against top side Adelaide at Etihad Stadium on Saturday night.

James Kelly, Matt Leuenberger, Matt Dea, Jayden Laverde and 2016 No.1 NAB AFL Draft pick Andy McGrath are the Bombers' inclusions.

Tom Bellchambers (foot), Orazio Fantasia (hamstring) and Zach Merrett (suspension) were the forced outs, while Michael Hartley was dropped and Mark Baguley was rested, although he is listed as an emergency.

The red-hot Crows are unchanged.

Another retiring star, Matt Priddis, has fought back from demotion to earn a spot for West Coast in Saturday night's match against Carlton at Domain Stadium.

Nathan Vardy and Lewis Jetta also return to the side in favour of Will Schofield, Chris Masten and Malcolm Karpany.

The Blues made a defensive swap, with Caleb Marchbank (arm) out for Tom Williamson.

Luke Hodge is back from suspension for the Hawks, who have also added Kurt Heatherley and Kade Stewart to their squad for the trip to Launceston to face North Melbourne. Hodge is the only confirmed inclusion, with the others on the extended bench.

The Kangaroos have made just one change so far, with two-gamer Nick Larkey omitted. Jed Anderson, Kayne Turner – after seven weeks out with a knee injury – Jy Simpkin and Cam Zurhaar are possible ins.

Friday, August 11

Western Bulldogs v Greater Western Sydney at Etihad Stadium, 7.50pm AEST

WESTERN BULLDOGS

In: J.Stringer, T.Dickson, J.Dunkley

Out: E.Wood (hamstring), C.Smith, L.Webb

GREATER WESTERN SYDNEY

In: T.Greene, J.Patton

Out: S.Mumford (suspension), D.Smith (knee)

Saturday, August 12

Sydney v Fremantle at the SCG, 1.45pm AEST

SYDNEY

No change

FREMANTLE

In:M.Taberner, J.Deluca, S.Darcy

Out: J.Griffin, H.Crozier (concussion), B.Grey (hamstring)

Geelong v Richmond at Simonds Stadium, 2.10pm AEST

GEELONG

In:P.Dangerfield, R.Stanley, S.Motlop, D.Menzel

Out: J.Selwood (ankle), T.Hawkins (suspension), M.Duncan (suspension), W.Buzza

RICHMOND

In: J.Riewoldt

Out: A.Miles

Brisbane Lions v Gold Coast at the Gabba, 4.35pm AEST

BRISBANE LIONS

In: M.Close, S.Mayes

Out: A.Witherden (hamstring), J.Schache

GOLD COAST

In: D.Swallow, J.Lyons, C. Ah Chee, B.Ainsworth

Out: G.Ablett (hamstring), J.Grant, M.Hallahan, T.Lynch (knee)

Essendon v Adelaide at Etihad Stadium, 7.25pm AEST

ESSENDON

In: J.Kelly, M.Leuenberger, M.Dea, J.Laverde, A.McGrath

Out: Z.Merrett (suspended), T.Bellchambers (foot), M.Hartley, O.Fantasia (hamstring), M.Baguley (rested)

ADELAIDE

No change

West Coast v Carlton at Domain Stadium, 5.40pm AWST

WEST COAST

In:M.Priddis, N.Vardy, L.Jetta

Out: W.Schofield, C.Masten, M.Karpany

CARLTON

In: T.Williamson

Out: C.Marchbank (arm)

Sunday, August 13

Melbourne v St Kilda at the MCG, 1.10pm AEST

MELBOURNE

In: J.Wagner, B.Stretch, A.Brayshaw, S.Weideman, M.Hannan

Out: S.Frost, C.Salem

ST KILDA

In: S.Gilbert, T.Hickey, D.McKenzie, J.Lonie

Out: N.Riewoldt (concussion)

Hawthorn v North Melbourne at UTAS Stadium (Launceston), 3.20pm AEST

HAWTHORN

In: L.Hodge, K.Heatherley, K.Stewart

Out: -

NORTH MELBOURNE

In: J.Anderson, K.Turner, J.Simpkin, C.Zurhaar

Out: N.Larkey

Port Adelaide v Collingwood at Adelaide Oval, 4.10pm ACST

PORT ADELAIDE

In: M.White, B.Ah Chee, C.Wingard, J.Neade, D.Howard, D.Houston, R.Bonner

Out: A.Monfries, J.Trengove, A.Young, J.Hombsch (hip)

COLLINGWOOD

In: T.Broomhead, J.Smith, J.Aish, M.Cox, C.Brown, J.Daicos

Out: D.Wells (quad), L.Greenwood (knee), B.Grundy (suspension)

New: Josh Daicos (Oakleigh U18)