PORT Adelaide is set to be without Brandon Zerk-Thatcher for the start of the season after the defender suffered a back injury.

Zerk-Thatcher, 26, sustained an acute lumbar disc injury during training on Wednesday.

The former Essendon backman has been ruled out of the pre-season games and the Power said he was expected to miss the start of the season proper.

A timeline for his return is expected to become clearer in the coming weeks.

Zerk-Thatcher was a key part of the Power backline in 2024, playing all 26 games as they reached a preliminary final.

Port could be without forward Todd Marshall for most of the 2025 season after he ruptured his Achilles in January.

The Power will face Adelaide in a match simulation on February 21 before taking on St Kilda in the AAMI Community Series on March 1.

Port begins its home and away season against Collingwood on March 15.