WITH its season on the line, Port Adelaide has dropped four players among five changes for its pivotal meeting with Collingwood at Adelaide Oval on Thursday night.

The Magpies are unchanged from the team that fell to Hawthorn by 10 points at the MCG on Friday night with ruckman Brodie Grundy overlooked.

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Fed up with the Power's inconsistent form, coach Ken Hinkley has dumped Tom Jonas, Nathan Krakouer, Andrew Moore and Sam Colquhoun. 

In a blow for Hinkley's side, Alipate Carlile has also been ruled out because of a back complaint. 

Key defender Jackson Trengove returns after missing last week's loss to the Sydney Swans with a virus, while Cam O'Shea, Tom Clurey, Jake Neade and Karl Amon have all been included in the Power's side.  

Trengove's inclusion looms as extremely important as he is the man most likely to be charged with the task of containing Magpies key forward Travis Cloke. 

Jonas has been struggling for form in recent weeks and Hinkley said earlier on Wednesday he needed the important defender to discover his best football back in the SANFL.

With Port languishing in 12th spot on the ladder, Thursday night is a must-win if it's to have any chance of playing finals. 

Pies ruckman Grundy, who made his return in the VFL last weekend after a scary neck injury sustained in a training mishap, has not been named despite travelling with the team on Wednesday. 

Highly-rated young defender Matthew Scharenberg is edging closer to making his debut for Collingwood and has also travelled with the team as an emergency. 

Scharenberg, the No.6 selection in the 2013 NAB AFL Draft, has endured a horror injury run since joining the Pies.

He had foot surgery last February to remove sesamoid bones, and then ruptured his left anterior cruciate ligament in a VFL game in August last year.

The 19-year-old has now played eight VFL games after returning from the knee reconstruction.

Thursday, 9 July
Port Adelaide v Collingwood, Adelaide Oval at 7.20pm AEST

Port Adelaide
In: J.Trengove, C.O'Shea, T.Clurey, J.Neade, K.Amon 
Out: A.Carlile (back), N.Krakouer, A.Moore, T.Jonas, S.Colquhoun 

Collingwood
No change