Hawthorn youngster Seamus Mitchell is set to miss at least the next month after suffering a fractured jaw on Thursday.
The incident occurred during a collision in match simulation, with subsequent scans revealing the extent of the 21-year-old's facial injury.
Hawthorn Head Doctor Liam West said Mitchell is set to undergo surgery early next week.
"Seamus had scans on Thursday afternoon which unfortunately confirmed a fracture of the jaw," West said.
"He will now see a specialist and then have surgery early next week. We will have a better idea on his timeline for return to play following that. But at this stage, we anticipate this to be somewhere between four to six weeks following his operation.
"It's an unfortunate result for Seamus, but we expect him to make a full recovery and he'll be doing everything he can to return to the field as soon as possible."
Mitchell produced a break-out debut campaign last year across his 14 games, which included a Rising Star nomination.