HAWTHORN star Sam Mitchell will be sidelined for about two months after scans revealed a serious hamstring injury suffered during the Hawks' 145-point win over St Kilda on Saturday.

The reigning premiers have also lost key defender Brian Lake to a calf strain, with scans showing that Lake's injury is bad enough to keep him out for up to four weeks.

Mitchell hobbled from the field late in the first quarter of the win over the Saints and was immediately subbed out.

"Sam unfortunately has got an intra-muscular hamstring tendon injury, which means he going to be out of action for about eight weeks," Hawks football manager Chris Fagan told hawthornfc.com.au.

"It's probably a similar injury to what Cyril (Rioli) had last year, and he missed around eight weeks.

"We just want to make sure that when he comes back he's fully fit, so unfortunately that's the case.

"But when one door closes, another opportunity will open up for somebody else."

Lake was injured during the third quarter, and his injury left the Hawks with just two men on the bench during the remainder of the second half.

"We expect that he'll be somewhere between three to four weeks," Fagan said.

"So both those guys will be out for the big clash this weekend against the Swans, and then we have the bye, which is probably fortunate.

"They're obviously disappointed, but their minds now switch to doing a really good rehab and making sure they're in great condition when they return."

If all goes to plan, Lake should be back on the park for Hawthorn's game against West Coast in Launceston in round 12.

Mitchell's best hope is to be back in action by the time Hawthorn takes on North Melbourne at Etihad Stadium in round 16.