FREMANTLE has locked away its newest NAB AFL Rising Star winner  - and last year's No.8 draft pick - Caleb Serong.

The exciting midfielder- who also took out the AFL Players' Association best first year player award - has signed a two-year extension on top of his initial two-year deal for the 2020 and 2021 seasons and is now tied to the club until at least the end of 2023.

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The 19yo joins fellow top-10 picks Liam Henry and Hayden Young as 2019 draftees who have signed contract extensions through to 2023. And on Thursday, the Dockers also handed emerging defender Brennan Cox a two-year contract extension (signed until at least the end of 2022).

"I just love the family feel around the club. Everyone is really close and it's a really young group," Serong told fremantlefc.com.au.

 "I think all the boys are really excited about what we can do and achieve with who we have here at the moment, I can't wait for the next few years." 

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Fremantle's player personnel head David Walls said:  "Caleb has bought in to the club, to Perth and to the Fremantle culture really well. He's been outstanding.

"We first saw his dedication and commitment in the COVID shutdown, where he went away and used that time as well as anyone to improve his running, make gains and come back fitter and better than before.

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"He's accepted every challenge that's been thrown at him by (senior coach) Justin Longmuir and (assistant coach) Josh Carr, taking on some of the game's best players and going head-to-head with them and handling that challenge really well."

Fremantle have gradually built a midfield for the future around Serong, as well as Brayshaw, Cerra and Darcy who were named in the AFLPA's 22under22 team.

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"We're seeing Sean Darcy develop as a young ruck and we have Andy Brayshaw and Adam Cerra who can be a real lethal combination for a long time," Walls said.

"They all complement each other really well and it's great for those guys, they've had David Mundy and Nat Fyfe to learn from, they're the experienced heads so we have a great mix in that midfield."