Hawthorn has lost veteran full-back Brian Lake to injury for about a month.



Lake twisted his left knee in a marking contest during the first quarter of the Hawks' eight-point loss to Port Adelaide last Saturday night.

The defender immediately hobbled from the field and had his knee strapped, but couldn't return to the action and was subbed out of the game soon after.



Lake will miss about a month and the Hawks now have four key defenders – including James Frawley (pectoral), Matt Spangher (hamstring) and rookie Kaiden Brand (shoulder) – on the sidelines.



"Brian had a scan yesterday and it revealed some damage to his medial ligament. We think he's going to be about four weeks. The good thing is he didn't have to go into a cast, or a brace," Hawks general manager of football operations Chris Fagan told the club's website.



"He was moving around quite well, so we're hopeful that he'll make a speedy return.



"But it's probably going to be around that four-week mark."



With the Hawks facing a major reshuffle of their backline against North Melbourne's tall timber on Saturday night, Fagan said there were several options to bring into the side.



"Guys like 'Gibbo' (Josh Gibson) in the past have played tall so they'll be required to do that and we've got young guys like Ryan Schoenmakers and Kurt Heatherley at Box Hill who can fill the void in key positions," he said.



"Timmy O'Brien as well, who played centre half-back for Box Hill at the weekend, so it might present an opportunity for one of those guys which is really good because they're all capable players."



The Hawks could also regain midfielder Liam Shiels for the important clash against North, with both sides sitting on 2-2.



Shiels has missed three games since he suffered a hamstring strain in the round one demolition of Geelong on Easter Monday.



Meanwhile, small forward Paul Puopolo should also be fit to face the Kangaroos.



Puopolo sat out most of the second half against the Power with an apparent corked leg.



The 27-year-old suffered a corkie when he ran into an umpire before the Hawks' round three win over the Western Bulldogs, but was passed fit to play Port Adelaide.



"'Poppy's' was more of a corkie than anything else that bled into his knee and it's causing a fair bit of pain," Fagan said.



"So they weren't quite sure whether it was a corkie or a muscle injury, but it looks more like it's a corkie so he's a good chance to play this week."