Petracca completed a light session with his teammates at Gosch's Paddock on Monday morning, albeit with a slight limp and with tape around his right calf, four days out from Friday night's do-or-die clash.
He suffered a hairline fracture of his fibula and corked calf in a collision with Sydney's Lance Franklin early in last Friday's qualifying final loss and was limited throughout the game.
"I saw him this morning just then, walked past him, he's looking alright," Lever told reporters before training on Monday.
"I think he'll have a bit of a lighter week. But he'd have to tick off a fair few things.
"For us that probably doesn't worry us that much in terms of him not training. He's done probably nearly every session all year and this time of year, maybe a little bit of a freshen up might be good for him.
"He was moving pretty well for a guy that has a broken leg. But he's pretty tough so he'll play.
"Like every other club, there's going to be a lot of injuries in finals time, not many players want to miss. You'd usually say a broken leg would only keep you out, but maybe in Trac's case it's not going to."
Lever played down fitness concerns over Charlie Spargo, who spent Friday night in hospital after a hit to the throat, and Bayley Fritsch, who played through a knee issue.
Both players were only walking laps on Monday morning, with Fritsch's left knee strapped.
Lever was on a modified program and trained inside instead of with the main group, but Melbourne officials said he would be fit to face Brisbane.
The defender was confident forward Tom McDonald could make an impact if called on, despite having just one VFL game to his name after a long-term foot injury.
McDonald made his return from a long-term foot injury in Casey's VFL qualifying final win on August 27 but wasn't selected against the Swans.
With no VFL game on the weekend, he instead completed a heavy training session on Saturday.
"He's a chance, he's a pretty important player for us," he said.
"I'm sure that Tom would have loved to play (VFL) last week in terms of getting a bit of continuity in his body, but I think he trained pretty solidly on Saturday.
"So if he's available then I'm sure the coach will have some thinking to do."
Like coach Simon Goodwin, Lever lamented "disappointing" lapses in discipline against Sydney, including three 50-metre penalties that led to goals, but stressed it was not a trend.
