Hawthorn held on for a thrilling three-point win over Melbourne at the MCG on Sunday afternoon, for the side's second win of the season.
However, the crucial win looks to have come at a cost, with defender Grant Birchall suffering a knee injury.
Birchall copped a knock to his right knee in a marking contest in the first quarter.
He reappeared from the rooms after quarter-time with ice on his knee and did not take any further part in the game.
Coach Alastair Clarkson said post-match the club is unsure of the exact extent of the injury, but admitted it is unlikely a short stint on the sidelines will follow.
"He's got a tweak to a knee โ we just don't know the severity of it," Clarkson said post-match.
"I'm not sure if that's going to mean he'll be right to play next week, I'd say it'd be doubtful.
"If you can't come back on in the first 10 or 15 minutes of doing an injury of that nature, then you're probably in a bit of trouble for next week.
"We'd imagine he's going to miss. It could be six weeks or it could be zero. But I'd reckon it's more likely to be one or two at this point."
The game was Birchall's first since breaking his jaw in round two.
Hawthorn host Brisbane in Launceston next Saturday afternoon.
