MELBOURNE coach Simon Goodwin has declared Norm Smith medallist Christian Petracca a certain starter for the Demons' semi-final against Brisbane.

The star midfielder is dealing with a hairline fracture in his right leg and a corked calf but Melbourne say Petracca will face the Lions at the MCG on Friday night.

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"He's 100 per cent playing," Goodwin said of Petracca on Thursday.

"He trained really well in our main training session and he'll train again today but we're really confident in terms of how he is.

"He's moving incredibly well and we've been really surprised with his progression throughout the week, and he's the type of competitor you want."

Petracca has trained this week following the issues suffered in a collision with Sydney superstar Lance Franklin during last week's qualifying final loss against the Swans.

The 26-year-old has also been spending time in a cryotherapy machine at extremely cold temperatures to help the calf heal.

Goodwin knows Petracca will need to play through some discomfort but has backed in the three-time All-Australian to thrive.

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"This is a great opportunity to put himself on a show with a little bit of adversity during the week," Goodwin said.

"The pain management's around his corkie, and making sure that's right.

"He's not the only player in the year so far that's had a corkie and had to come up and play so he'll be right to go."

Petracca was clearly hampered by his leg issues for most of the match against the Swans, hobbling to contests, and had nowhere near his usual impact as the reigning premiers suffered a shock defeat.

"He'll be in the midfield, he'll play forward, he'll play a variety of different roles that sit within our game methods," Goodwin said.

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Petracca won't be the only sore Demons player out there, with gun goalkicker Bayley Fritsch (knee) and small forward Charlie Spargo (throat) having a lighter week on the track.

Fritsch was one of Melbourne's best against the Swans, despite some pre-game concern around his knee.

Spargo copped a knock to his throat but was cleared of any serious damage.

Melbourne is also weighing up whether to bring in premiership forward Tom McDonald following a long-term foot injury.

McDonald last played AFL in round 10 but did make an appearance for the Demons' VFL team a fortnight ago.