New Carlton co-captain Sam Docherty has suffered the same knee injury that sidelined him for this AFL season.
It is a devastating blow for the Blues and for Docherty, who now faces another barren year out of the game.
The Blues have confirmed that Docherty ruptured the anterior cruciate ligament in his left knee while training on Monday morning.
Medical staff were initially positive but Docherty immediately went for scans, which confirmed the worst.
The 2016 club best and fairest and 2017 All-Australian had a reconstruction after suffering the initial injury in November last year.
Docherty, 25, made a strong recovery and had returned to full training before this latest setback.
It is too early to say, but another reconstruction appears his most likely option.
He and Patrick Cripps took over from Marc Murphy as Carlton's new captains.
Last week, Docherty spoke about the mental challenge of returning from a knee reconstruction.
"You lose the mental challenge in terms of my knees because you do so much of the stuff you're scared about," he said.
"The first time I ran I was scared. The first time I changed directions I was really scared. The first time I did a high mark I was scared
"Over repetition of doing that, you lose that."
Docherty is a highly-respected AFL player and a much-loved figure at Carlton.
"It's clearly a huge disappointment for Sam to experience such cruel luck, we are all feeling for him right now," said Blues' football boss Brad Lloyd.
"The way he tackled his rehab this year was simply incredible and he could have played at the end of last season before the decision was made to hold him back.
"If the last 12 months have shown anything, it's that Sam is made of everything that is required to return to his elite best once again."
Carlton finished last this season with only two wins, but expectations are high that they will improve significantly next year.
The Blues were bold at the draft last month, trading next year's No.1 picks with Adelaide in a deal that secured them midfielder Liam Stocker.
The clear message from that trade is that Carlton expect to finish higher on the ladder next season.