Melbourne forward Daniel Turner has been subbed out of the Demons' clash with Fremantle after suffering a concussion.
Turner came from the ground towards the end of the second term and underwent a head injury assessment, which returned a failing result.
Turner had recorded five disposals and three marks to halftime, including a welcome intercept mark in the last line of defence, as he and Harrison Petty exchanged roles for the game.
Despite pre-season comments that Petty's forward line trial was over, the key position tall has claimed three majors to the half, as well as a goal assist to on-fire small forward Kysaiah Pickett, who has his own four goals.
2024 off-season recruit Harry Sharp replaced the concussed 23-year-old after being handed the substitute role for Saturday's match.
Demons coach Simon Goodwin said the Demons will provide as much time as necessary for the youngster to recover.
"He'll get assessed, he goes straight into the protocols and we'll give him as much time as he needs as a footy club," Goodwin said.
"We'll certainly rely on our medical team and our high-performance team to make sure that he's fit when he's right and ready to come back."
Meanwhile, Fremantle midfielder Jaeger O'Meara also missed the final term with a leg concern, which Longmuir later confirmed at the post-game press conference to be a hamstring complaint.
The injury came just moments after Fremantle made the tactical substitution of Bailey Banfield off the field for Isaiah Dudley.
"It looks like he might have done a little whammy, so fingers crossed," Longmuir said.
"That's what it looks like so far."
The Dockers have now dropped to 3-3 and will have to rebound against the dangerous Adelaide Crows, while the Demons will look to make up for their 0-5 start with back-to-back wins against Richmond in the ANZAC Day Eve blockbuster.
