Lance Franklin won't play another AFL match until 2021 after Sydney's medical team made the call to put the superstar on ice.
Franklin suffered a serious hamstring injury in May and had been hopeful of returning late this season.
But an increase in his training program in recent weeks has resulted in some groin soreness.
The Swans are well out of finals contention and have opted to rule Franklin out of the remaining four matches of the home-and-away campaign.
"Lance has been working hard on a return to play and, until this week, we remained hopeful that would happen before the end of the season," Sydney football manager Charlie Gardiner said.
"However, given the soreness he has experienced in his groin, which suggests he still has some instability there, we believe the best course of action is for Lance to focus on building his core strength, rather than pushing himself to play again this year."
Franklin has been in Perth with Sydney's travelling party and will stay with them as they base themselves in Queensland to see out the rest of the season.
"Lance will remain with the team and continue his rehabilitation and training," Gardiner said.
"He's also keen to assist in a mentoring and coaching capacity as he is fully invested in our young group.
"We look forward to seeing him back to full strength next season."
Franklin has not played a single match in the seventh year of the massive nine-year deal he signed with Sydney upon leaving Hawthorn.
The 300-game veteran turns 34 in January and is 56 goals away from becoming the sixth player in AFL-VFL history to reach the 1000-goal mark.