Scans have confirmed Hawthorn forward Mitch Lewis has suffered a sprain of his anterior cruciate ligament following an incident at training on Monday.

Head Doctor Liam West says early signs suggest the injury will not require surgery.

"We will monitor Mitch's progress closely over the coming weeks," West said.

"He will certainly spend some time on the sidelines though and, at this stage, we expect him to miss Round 1.

"Whilst this is the same knee he injured last season, it is an unrelated injury."

The club will provide further updates in due course.