Clayton Oliver is taking extended leave to deal with personal issues, with no immediate indication on when the Melbourne star will return to the AFL.
The four-time club best-and-fairest winner did not attend pre-season training on Thursday with his teammates.
It is the latest setback for Oliver, who has battled injuries and medical issues as well as facing questions about his off-field behaviour.
Oliver left Melbourne's December training camp in Lorne early to deal with medical problems.
The Demons released a statement from football boss Alan Richardson when Oliver did not join his teammates on Thursday morning at Melbourne's Casey Fields training base.
"Clayton has personal issues that he has been dealing with," Richardson said.
"Clayton has been working extremely closely with his personal medical team, and with the support of key club staff, in order to manage these challenges.
"The club fully supports Clayton taking this important time out, which will allow him to focus on these challenges.
"Our primary focus is Clayton's overall wellbeing, and we will continue to support him through this period.
"It's important for Clayton that we respect his privacy and his need for time and space."
Oliver's professionalism was repeatedly questioned in 2023 amid doubts over his future at Melbourne.
The triple All-Australian was restricted to 15 games last season because of a drawn-out hamstring injury but returned before finals, when the Demons made a second consecutive straight-sets exit.
Oliver was later the subject of intense trade speculation, with Adelaide among the clubs interested, despite being under contract until 2030 after signing a massive seven-year extension.
Melbourne ultimately did not put him on the trade table.
Coach Simon Goodwin said in October he had never considered trading Oliver, but he and chief executive Gary Pert made it clear the midfielder needed to adhere to the Demons' standards.
Melbourne's culture has been under fire amid Oliver's troubles, plus utility Joel Smith's provisional suspension for recording a positive in-season drugs test to cocaine.
Oliver said he did not want to leave the AFL club, where he was a star of their 2021 premiership, but had been prepared to depart if Melbourne no longer wanted him.
In an interview on October 31, the 26-year-old also committed to knuckling down and meeting Melbourne's standards.
Oliver was pulled over by police on November 16 and charged with driving with a suspended licence.
He has been unable to drive on medical grounds since he was hospitalised following a seizure on October 12, which he partially attributed to side effects of his ADHD medication.
Oliver is due to face court on February 6.
