HAWTHORN will sweat on the outcome of scans on the right knee of Grant Birchall, with coach Alastair Clarkson suggesting the star defender could be sidelined for up to six weeks.

Birchall left the field late in the first quarter of the Hawks' stirring three-point win over Melbourne at the MCG on Sunday with a suspected posterior cruciate ligament injury.

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Clarkson hasn't yet ruled Birchall out of Hawthorn's clash with the Brisbane Lions in Launceston next week, but conceded a stint on the sidelines was highly likely.

"He's got a tweak to a knee – we just don't know the severity of it," Clarkson said at his post-match press conference.

"I'm not sure if that's going to mean he'll be right to play next week (but) 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."

WATCH: Alastair Clarkson's full post-match press conference

Birchall was the second Hawk for the day to succumb to a knee issue, given star recruit Jaeger O'Meara was a late withdrawal with knee soreness that will likely require several weeks of recovery.

Clarkson was particularly proud of him team's efforts to overcome the Demons despite the personnel issues.

The Hawks led by 35 points early in the third quarter before Melbourne stormed back to level the scores early in the final term, only for Hawthorn to stand firm.

It was just the Hawks' second win for the season after suffering heavy defeats in three of their past four outings.

"It was a tough week. We were really disappointed with our effort against St Kilda last week, but that's the fickle nature of the game.

"We beat Melbourne, Melbourne beat St Kilda, and St Kilda beat us – that's probably a reflection of the closeness of the season.

"We haven't played our part in the bargain too much to this point, and we're hoping this is just a little step forward for us, but we're very, very mindful that we thought (defeating) West Coast was going to be a step forward for us two weeks ago (but) our effort the next week was far, far below par …

"What was pleasing today was that we were challenged significantly in the third quarter and we found a way to regroup and get ourselves a pretty important win."

Clarkson revealed he was frustrated by the lack of holding-the-ball free kicks awarded to his team.

"We tackled pretty well (but) it's frustrating that not many of the tackles are getting rewarded," he said.

"There's (163) tackles laid between the two sides today and 26 free kicks paid – and a lot of those free kicks wouldn't be to do with the tackling.

"That's frustrating for coaches, for players, for those that are watching from the sidelines.

"It means the game is pinged around with a lot of handball and it just makes it difficult to give an even balance between the ball (carrier) and the tackling player.

"That's not going to change overnight, I understand that, but the balance is a bit skewed towards the ball-handler at the minute."