PORT Adelaide has delisted untried Jake Patmore after three years at the club.

Patmore arrived at Alberton with pick 58 in the 2017 NAB AFL Draft from Claremont, but after a strong first season in the SANFL, was struck down by bad luck.

The 21-year-old missed the entire 2019 campaign after rupturing his anterior cruciate ligament in a trial match.

WHO'S LEAVING? Your club's retirements and delistings

General manager of football Chris Davies said things didn't get much better from there for Patmore.

"Jake is a real victim of circumstance; with an ACL injury in 2019 being compounded by a lack of regular competitive football in 2020 due to COVID, and what will be a reduction in list sizes for 2021," Davies said.

"He is an outstanding young man who has demonstrated great professionalism, but we have had to make this difficult call based on our list numbers for 2021."

Patmore is the sixth Power player to be delisted, following Joe Atley, Wylie Buzza, Tobin Cox, Riley Grundy and Cam Sutcliffe.

INDICATIVE DRAFT ORDER Your club's picks as they stand

Meanwhile, the Power have extended the contract of defender Martin Frederick until the end of 2021.

Frederick is yet to debut at AFL level but has featured 20 times for the club at SANFL level since being picked up as a Category B rookie at the end of the 2018 season.

The Next Generation Academy product is a speedy rebounding defender.