PORT Adelaide is set to retain former Melbourne co-captain Jack Trengove and ex-Gold Coast defender Trent McKenzie for another season.

AFL.com.au understands the pair will sign one-year extensions to remain at Alberton in 2019.

The Power will also re-contract rookie-listed ruckman Peter Ladhams, while they are yet to decide if they upgrade untried midfielder Cam Hewett to the senior list or delist him.

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Trengove and McKenzie joined the Power last year as delisted free agents.

Trengove played three games for the Power across half-back and was one of Port Adelaide's best midfielders in the SANFL.

The 27-year-old has played 89 AFL games since being selected with the No.2 overall pick in the 2009 NAB AFL Draft.

Trengove was appointed as co-captain of the Demons in 2012, but was sidelined for two seasons with chronic foot injuries before he was delisted at the end of 2017.

McKenzie played one game for the Power this year and provides defensive depth.

The 26-year-old played 106 games for the Suns from 2011-17.

Ladhams, 20, has spent the past two seasons at the Power after being taken with the No.9 overall pick in the 2017 rookie draft.

The 203cm, 94kg big man has worked on his craft in the SANFL.

He is the fifth ruckman on the Power's books after they acquired West Coast premiership player Scott Lycett as a free agent.

Lycett and All Australian ruckman Paddy Ryder will be the Power's first-choice ruck pairing, while Billy Frampton – who debuted in round 23 this year – and Ladhams are waiting in the wings.

Ladhams has been retained so the Power don't have to rush promising 19-year-old Sam Hayes back as he recovers from a torn ACL sustained in June this year.

Hayes, a dual under-18 All Australian ruckman, was taken with the 47th pick in last year's draft.

Hewett, 21, has spent the past three seasons on the Power's rookie list.

Under League rules, that's the maximum time a player can spend on a rookie list before he has to be either upgraded to the senior list, or delisted.

The Power have until the list lodgment deadline of October 31 to make a decision.

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Not including Hewett, the Power will have 35 players on their senior list.

Pressure forward Jake Neade, winger Dom Barry and rookie-listed midfielder Will Snelling were delisted on Monday, while impressive defender Dan Houston was upgraded to the senior list.

Key defender Jarrod Lienert and Ladhams are the Power's only two rookies at this stage.

The Power currently have picks 5, 10, 15 and 85 in the NAB AFL Draft.

In other previously announced list changes, half-back flanker Jimmy Toumpas and rookie Emmanuel Irra have been delisted, while rookie-listed veteran forward Lindsay Thomas has retired.

Lycett, Hawthorn's Ryan Burton and Brisbane's Sam Mayes have joined the club via trade, while Chad Wingard (Hawthorn), Jared Polec (North Melbourne), Jasper Pittard (North Melbourne) and Jack Hombsch (Gold Coast) found new homes during the Trade Period.