The Dockers have taken an extended squad of 30 players with them for games against Brisbane (Gabba) and Essendon (Marvel Stadium).

Treacy was dropped after the round-six win over North Melbourne after going goalless from his third straight match.

The 18-year-old found some form with a five-goal haul in the WAFL last week, but he was a notable absentee when the team flew to Brisbane on Wednesday.

Longmuir said it was important for Treacy to get WAFL games into him rather than travel with the senior squad and be left on the outer.

"It's probably mainly around him missing a lot of footy at the start of the year through suspension," Longmuir said.

"And he's got some things with his forward craft that he can really work on this week.

"We've got a bye (in the WAFL) next week, so with the travel he'd miss two games of footy (if he came with us now). It's just about getting him some continuity."

Fremantle were originally scheduled to host the Lions at Optus Stadium on Sunday, but the game was switched to Brisbane due to Perth's recent COVID-19 scares.

Longmuir said it was up to his team to roll with the punches.

"Of course ideally we'd love to be playing at home in front of our crowd, with Brisbane travelling," Longmuir said.

"But we always knew this season was going to have some disruptions. Brisbane went through it earlier in the year, and it's our turn this time.

"And luckily we get the fixture swap later in the year. We just have to cop it on the chin."

The Dockers will be without defenders Ethan Hughes and Heath Chapman against the Lions after they suffered shoulder injuries in last week's 59-point western derby loss to West Coast.

Chapman could miss about three months of action if it's deemed he needs a full shoulder reconstruction.

Longmuir is confident midfielder Adam Cerra (ankle) will return for next week's clash with Essendon, while Alex Pearce (ankle) could return the week after.

Australian Associated Press