Fremantle is facing an anxious wait to see if influential ruck veteran Aaron Sandilands will be fit for a tough away clash against Collingwood after a heavy collision with North Melbourne youngster Sam Durdin on Sunday. 

Sandilands went to bump Durdin as he closed in on teammate Stephen Hill and they clashed heads, leaving them dazed and needing assistance from the field.

Neither player returned to the action but Sandilands appears to have come off worst after suffering concussion.

The 35-year-old was wobbly coming off the ground and is in doubt for the Dockers' trip to the MCG.

"It's not my decision. It will be medical, but clearly it's a mitigating factor and a contributing variable, a concern," coach Ross Lyon said.

"We won't risk him. He's done everything he's had to do for this club, virtually.

"It would err on the side of being conservative, which we do with all our players."

Sandilands has played all 10 games this season, with Lyon feeling unable to give the 211cm giant a rest due to Sean Darcy being unavailable with a PCL injury.

Michael Apeness led the ruck for Peel in a shock loss to East Fremantle on Saturday and shapes as the likely replacement, with Scott Jones and Luke Strnadica other options.