Sydney coach Dean Cox has conceded the Swans are bracing for the worst news about captain Callum Mills.
Mills came from the ground early and was unable to weight bear on his right knee as two trainers helped him off with immediate fears being he may have suffered an ACL rupture.
"I'm not expecting great news on Callum and we'll in the next couple of days find out the extent of that which is devastating for him and the footy club," Cox said.
"We'll do whatever we can to support him through what he's going to go through.
"The maturity of the group to rally and stay on tasks with what they had to do is a credit to them."
The incident occurred deep in the first quarter, with Mills' knee collapsing from under him as he attempted to change direction to pressure Brisbane's Will Ashcroft.
Minutes after he came he was limping around on the boundary line before promptly going down to the race.
The Swans proved too strong for the Lions, with their stoppage ascendancy, marking forwards and interceptors overwhelming a Lions outfit ill-equipped for the pressure the Swans brought.
