Richmond forward Tom Lynch has entered concussion protocols following a knock at training on Friday.
The incident and setback will see Lynch out of action for the next 12 days at least, potentially seeing him miss the club's first match of the pre-season.
Lynch has been working his way back from a long-term foot issue and hamstring injuries that plagued his 2024 campaign. The one-time Jack Dyer Medal winner played just four games last year, adding to his four matches the year.
The star forward had enjoyed an uninterrupted summer so far, with the club hopeful he'll be available for at least one pre-season hitout.
"'Lynchy' can't take a trick, he's entered concussion protocols," Richmond assistant Steve Morris said.
"He's had an outstanding eight weeks of training. He's firing on all cylinders and is just training with some real purpose.
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"It's a bit of a speed bump for him, but he's in really good nick and we hope to see him back in the really near future."
Richmond are also hopeful key defender Jacob Blight has avoided a significant shoulder injury following an incident at training.
Blight came from the Punt Road track holding his shoulder and did not return for the rest of the session.
The Tigers believe their 2024 Mid-Season Draft addition won't be overly hampered by the scare.
"I think he's got away with one there," Morris said of the Blight incident. "We hope to see him full training again next week."
Veteran Dion Prestia was limited during Friday's match simulation session, playing just a third of the hitout before resting.
The Tigers head to Western Australia in mid-February for their first pre-season game, with a Community Clash against Collingwood to follow.
Round 1 will see Richmond face Carlton on Thursday, March 13 to start their season proper.