Sandilands fractured his cheekbone during Sunday's 95-point win over Melbourne at the MCG.
The 189-game veteran will undergo surgery later this week, but the Dockers are "upbeat" he will be fit to play in the round-23 clash with St Kilda.
Fremantle goalsneak Hayden Ballantyne has been cleared of a serious shoulder injury, but is also set to miss Saturday night's home clash with Port Adelaide.
Scans on Monday confirmed Ballantyne had strained his right shoulder capsule, and the Dockers are likely to take a cautious approach with the 26-year-old ahead of the finals.
Sandilands, who underwent surgery on his hamstring earlier this year, will enter the finals series short on touch and match fitness after playing just six games this season.
However, the emergence of Zac Clarke in the ruck means Sandilands no longer has to carry the bulk of the ruck load.
Fremantle pair Garrick Ibbotson (achilles) and Clancee Pearce (calf) are on track to return against the Power, while defender Luke McPharlin (calf) is set to return a week later.
The Dockers sit in fourth spot on the table, but are still a chance to secure a top-two berth if Geelong loses one of their two final games.
Port Adelaide need one more win to guarantee their spot in the finals.