Sydney has ruled Aliir Aliir out of the grand final.
The young defender was unable to get through training on Wednesday after injuring his knee in a marking contest against Geelong.
The Sudanese refugee shaped as one of the feel-good stories of this year's decider.
Swans Head of Football Tom Harley said it was a tough situation for the club.
"Aliir has done all he could to give himself a chance to play, (but) unfortunately he was unable to complete training and therefore can't be considered for selection this week," Harley said.
Co-captain Jarrad McVeigh (calf) and Rising Star winner Callum Mills (hamstring) both remain in contention for a return.
