MELBOURNE, AUSTRALIA - APRIL 11: Tom McDonald and Adam Tomlinson of the Demons walk off the field after a win during the 2021 AFL Round 04 match between the Melbourne Demons and the Geelong Cats at the Melbourne Cricket Ground on April 11, 2021 in Melbourne, Australia. (Photo by Dylan Burns/AFL Photos via Getty Images)

Melbourne forward Tom McDonald will undergo scans on an injured foot that forced him out of Saturday night's clash with Sydney prior to the opening bounce.

The Demons confirmed McDonald was a late withdrawal ahead of the Round 12 bout, with ex-Cat and Bomber Mitch Brown coming into Simon Goodwin's side.

Despite having trained throughout the past week after missing his side's loss to Fremantle in Round 11 with ankle soreness, McDonald is still battling the injury and could be set for an extended period on the sidelines.

Fears of a Lisfranc injury are yet to be ruled out from the Demons' camp, with Goodwin acknowledging the worry after his side's two-goal loss to the Swans.

"He obviously trained throughout the week and he's still a bit sore, so we've got to go away and ... look a bit deeper into that and find out the reasons why," he said.

"He will have some scans early in the week and we'll get a bit more information and be able to pass it on at that point.

MELBOURNE, AUSTRALIA - AUGUST 18: Max Gawn and Tom McDonald wrestle during a Melbourne Demons AFL training session at Gosch's Paddock on August 18, 2017 in Melbourne, Australia. (Photo by Robert Cianflone/Getty Images)

"It's something we've got to look at with the foot. He's clearly still sore so we've got to dig a bit deeper."

A Lisfranc injury could see McDonald's season in some doubt, with the diagnosis commonly requiring a lengthy road to recovery.

The 29-year-old played nine of the Demons' opening 10 matches in their undefeated start to the season, booting 15 goals.

Goodwin will be able to rely on his deep key forward stocks in McDonald's expected absence, with fringe forward Sam Weideman also on offer at the selection table after booting a game-high three goals and taking 10 marks for Casey on Saturday.

Mitch Brown was kept goalless from eight disposals on Saturday night, while first-string spearhead Ben Brown was also unable to impact the goals and collected just four possessions.

The Demons will also look to monitor the health of key defender Harrison Petty, who suffered leg and shoulder issues against the Swans.

Melbourne will face Collingwood in Round 13 for the annual Queen's Birthday clash on Monday, June 13, where they are likely to regain star backman Steven May from concussion.