Dixon missed last Saturday's loss to Geelong after suffering a setback at training last week, with further investigations into the ailment uncovering a small crack under the middle section of his foot.
While the 32-year-old won't require surgery, Dixon will need approximately a month on the sidelines, placing him in doubt to play again before finals.
With no delays, Dixon would be expected to return for the club's opening finals game - likely to be a qualifying final in mid-September.
The injury blow comes as the Power look to land a top two finish and claim a home final in week one of the post-season, with Ken Hinkley's side potentially needing a perfect run in their final three games to move back into the top two.
The Power will be without defender Trent McKenzie until finals as well, with a PCL knee injury sidelining the backman for up to five weeks.
Ruckman Scott Lycett (knee) is also facing a period on the sidelines after requiring surgery, while defensive pair Aliir Aliir and Lachie Jones are expected to make returns this week after being placed into the AFL's mandatory concussion protocols.
Port Adelaide will host GWS at Adelaide Oval on Sunday at 4:40pm (AEST).