PORT Adelaide continues to lock away its young defenders, with Dan Houston agreeing to terms on a two-year contract extension.

AFL.com.au understands that the 20-year-old recently finalised a deal that will keep him at the Power until at least the end of 2019.

Houston has made 10 appearances for the Power this season, averaging 16 possessions, six marks and 2.5 tackles per game.

He joins key defenders Tom Clurey (23 years old) - who re-signed on Wednesday - and Jack Hombsch (24) in putting pen to paper on new two-year deals with the Power this year, while Darcy Byrne-Jones (21) is already committed until the end of 2018.

The Power used the 45th pick of the 2015 rookie draft to select Houston, who at that stage was regarded as a half-forward in the mould of Adelaide star Tom Lynch.

Houston was moved to defence midway through last year when he was playing for Port Adelaide in the SANFL.

His excellent form during the JLT Community Series was rewarded with him being elevated to the senior list and making his AFL debut in the Power's round one victory against Sydney at the SCG.

Houston held his spot for the first seven rounds before being dropped for the historic game against Gold Coast in Shanghai.

Since returning to the side in round 13, he has looked assured in the past three games and had a career-high 21 possessions in last weekend's 13-point loss to Richmond at Adelaide Oval.