HAWTHORN coach Alastair Clarkson confirmed key defender Brian Lake strained his medial ligament early in Saturday night's eight-point loss to Port Adelaide, but he'll have to wait on scans to release the extent of the injury. 

Lake tried to barrel Power spearhead Jay Schulz out of a contest deep in attack in the opening term, twisting his knee in the process. He tried to continue after having his left knee strapped only to be subbed late in the quarter for Billy Hartung. Clarkson would be amazed if Lake was fit to take on North Melbourne next Saturday. 

"He's got a medial ligament strain, we're uncertain of the severity of it though," Clarkson said. 

"I'd suggest, because he couldn't come back on tonight, it was just too unstable, that he'd be very, very unlikely to play next week." 

Port made its luck with superior toughness: Clarkson

Lake's injury clearly played a crucial role in the contest of the game against the Power, as that of James Frawley did against Essendon in round two. On both occasions the subbing of the key defenders resulted in the Bombers and Power kicking away.

The striking similarities were not lost on the coach. 

"I don't think there's a side in the competition that copes well when a key back goes down, and in both instances Frawley went down in the Essendon game and Lake went down in this game," he said. 

"With every other position on the ground, even if a ruck goes down you've got a second ruck but you haven't got a key back sitting on the bench. 

"In both games we just lacked a bit of stability for a period of time while we just tried to work out the balance of that and it's been costly for us twice." 

With both key backs on the injured list, Clarkson now faces a difficult job structuring the Hawks in defence. Frawley (pectoral) and Matt Spangher (hamstring) remain a month away, while youngster Kaiden Brand (shoulder) might only return to the selection mix late in the year. 

Ryan Schoenmakers looks primed for a senior return after two weeks as emergency. Clarkson confirmed Schoenmakers was available for selection and insisted only that the Hawks would "work out a way" to manage its defensive issues.