Western Bulldogs youngster Aiden O'Driscoll has been forced to retire just six months after being drafted after failing to recover from a "significant" head injury during a pre-season training session.
O'Driscoll, who was taken with the 55th pick in the 2023 AFL draft, will retire having not played a single AFL match.
He is the third AFL player to retire due to concussions this year, following Melbourne's Angus Brayshaw and Collingwood's Nathan Murphy.
In a statement released on Tuesday afternoon, the Bulldogs said O'Driscoll was advised to retire "following extensive clinical assessments, investigations and expert consultation that included a review by an Independent Medical Concussion Panel… in the interests of his long-term health and wellbeing".
O'Driscoll, the brother of Fremantle footballers Nathan and Emma, recorded the best 20-metre sprint time at last year's AFL draft combine.
The Bulldogs were enamoured with O'Driscoll's athletic attributes at the time of last year's draft, with the club's recruitment boss Dom Milesi calling him "clearly the best athlete in the pool".
The Bulldogs vice-captain is sidelined indefinitely after two separate concussions this season, with no timeline on a return to play.
Coach Luke Beveridge indicated Liberatore could be put forward for independent assessment, but said it hadn't been confirmed yet.
"With the recent retirements in young Murphy and Angus Brayshaw and some of the uncertainty around a couple of players who have had recent concussion, my level of concern around Tom is significant, because it's an unknown," Beveridge said on Fox Footy on Monday.
"Ultimately we've got to defer to the experts and medical practitioners as far as opinions go.
"I can't talk about the clinical side of things, but him as a young man and what he's done for all of us, I just hope he's going to be OK.
"We hold out a strong hope he might be able to play again, but ultimately the best result will be the result for Tom Liberatore's wellbeing."
O'Driscoll's retirement comes as the AFL continues to emphasise protecting players' heads amid the ongoing class-action lawsuits over concussions.
In March, the AFL increased the wait time for concussed community footballers before returning to training to three weeks, but did not amend the protocols for the elite level, with AFL players required to sit out for a minimum of 12 days after a concussion.
This week, AFL boss Andrew Dillon was forced to shoot down suggestions that the league should introduce independent doctors to assess head injuries.
Dillon was forced to respond after Geelong star Jeremy Cameron was allowed to remain on the field after a heavy fall that saw his head hit the ground in a marking contest.
While Cameron passed an on-field concussion assessment from a Geelong doctor, he was then placed into the AFL's concussion protocols following the match after reporting delayed symptoms.