Fremantle suffered a massive blow on the eve of the 2024 AFL season, with ruckman Sean Darcy sustaining a knee injury that has ruled him out indefinitely.

Darcy - who was reported sore following the first practice match against West Coast - was taken from the ground in the clash with Port Adelaide at half-time with knee pain.

After getting a scan on Sunday, the club revealed that the ruckman will need a left knee arthroscope.

Dockers Football Manager Joe Brierty gave some insight into Darcy's injury but wasn't able to give a clear timeline.

"Following specialist advice it was agreed with Sean that the best course of action was to complete an arthroscope to remove some of the loose bodies that were identified from the scan to be causing the discomfort," Brierty said in a club-issued statement.

"This procedure will enable Sean to get back to full fitness after an initial reloading period post the procedure."

Darcy's knee injury is another setback for the 25-year-old, who missed the last six weeks of 2023 following ankle surgery.

However, the club has faith that the 203cm ruck is still their man, having locked him away late last year until the end of 2030.

Darcy's absence will force coach Justin Longmuir to throw some magnets but will undoubtedly turn to Luke Jackson for the extra responsibility.

If Longmuir were to continue with the two-ruck approach, Liam Reidy, Osin Jones and Max Knobel - who are all untried at the AFL level - could be brought in to assist the former Demon.

Wingman Nathan O'Driscoll is also required to undergo surgery to remove a blood clot from his right knee.

“Nathan will be off-feet for a couple of days after the procedure, but it is expected that we will recover quickly from the procedure,” Brierty said. 

“Once he ticks off his load progressions, he should be able to transition back into football fairly quickly.”

Fremantle kicks off their 2024 season with a clash against Brisbane on Sunday, March 17 at Optus Stadium.