Hawthorn is expecting key defender Tom Barrass to be sidelined with a hamstring injury, which generally is a minimum of three weeks.
Barrass went down in the second quarter, which proved to be a significant moment in the contest and ultimately cost the Hawks a victory on the road.
The ripple effect caused Josh Weddle to play tall in defence, while the forward mix was "compromised" as players like Jack Ginnivan and Connor MacDonald were pushed further up the ground.
"Looks like he's done a hammy," coach Sam Mitchell said.
"We'll wait for scans over the next couple of days. I suspect it'll be a stint on the sidelines.
"Losing your fullback is never ideal. We had to push Weddle into the backline which compromised our forward structure a bit.
"We've got Ginnivan and MacDonald and these guys playing on the wing a lot. So it compromises you a lot. There's no excuse; we should've been better tonight."
Fremantle overwhelmed the visitors at Optus Stadium, piling on 22 inside 50s to four in the fourth term, which was largely due to the clearance dominance (12-4), helping turn a 15-point deficit at the final change into a 15-point win.
"We couldn't find any way to get any field position and just get the ball into our front half. So we got taught a bit of a lesson late," Mitchell said.
"We've talked a lot this year about being ready to play and win against the best sides, and we proved tonight that we're not quite there.
"We shot ourselves in the foot with the way we set the game up tonight, late in the game.
"We knew we were going to be up against it, and we were going to have to play 120 minutes. Unfortunately, 90 won't get it done against the Dockers, and we learned that lesson. Hit us right in the face to be fair."
For the second week in a row, the Hawks have failed to come away with the four points despite being in winning positions.
There's a watch on goal-kicking veteran Jack Gunston, who was limping around late in the contest.
Mitchell was positive about Gunston's corked foot, saying he returned to the field despite the ailment.
The Hawks will look to turn it around next week against Melbourne. Jack Scrimshaw looms as the likely replacement for Barrass.
