MELBOURNE superstar Christian Petracca has suffered a hairline fracture of his right fibula as well as a corked calf, but the Demons are still backing the gun midfielder to line up in their semi-final against Brisbane.

Petracca was proppy throughout Friday night's 14.7 (91) to 10.9 (69) qualifying-final loss to Sydney at the MCG after copping a stray boot to his upper right calf in an awkward first-quarter collision with Lance Franklin.

The Norm Smith medallist had scans on Saturday which confirmed the "minor" fracture, but the Demons are more concerned about the corked calf that limited him against the Swans.

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"The advice from our medical team is that a fracture of this nature will not rule Christian out of selection for our semi-final," Melbourne football boss Alan Richardson said in a statement.

"The fracture poses no further risk to Christian and will not impact his ability to play.

"What will pose more of a challenge for Christian is the corky he sustained to his calf in a collision that occurred in the first quarter and hampered his movement for the majority of the match against Sydney.

"Obviously Christian will need to tick some boxes throughout training this week but we are confident that he will be ready to go come Friday."

Petracca lacked his usual explosiveness on Friday night due to the "contusion" in his calf, but played out the game and battled his way to 24 disposals and four clearances.

"He was pretty sore," coach Simon Goodwin said.

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"Clearly, it limited his movement for the majority of the night and had a bit of an impact on his game."

Goodwin said Tom McDonald, who recently returned from a foot injury via the VFL, would complete a big training session on Saturday but wouldn't be drawn on whether he'd call upon the athletic tall to face the Lions.

Clayton Oliver was taped up after a cut eyebrow but Goodwin said there were no concerns over a potential fracture, while Bayley Fritsch pushed through pre-game concerns over his knee.

Goodwin was frustrated with multiple lapses in discipline against Sydney, which included three 50-metre penalties that cost goals and utility James Harmes being reported for a high, late hit on Swans defender Jake Lloyd.

Toeing the line better will be crucial against Brisbane, especially if the semi-final is as spiteful as their round-23 clash.

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"Finals footy's about getting the basics right for a long period of time and you need to be a disciplined footy team all the time," Goodwin said.

"So if you give away 50-metre (penalty) goals or downfield free kicks or give up territory through downfield reversals that cost you goals, that hurts.

"In tight games, where the stakes are high, that hurts."