JARRAD McVeigh's leadership is what the Sydney Swans will miss most if the co-captain can't take his place in Saturday's Grand Final against the Western Bulldogs.

McVeigh suffered a minor calf strain in his side's semi-final win over Adelaide, and must prove his fitness to Swans coach John Longmire and the club's medical staff at training on Wednesday.

If McVeigh gets through the session and pulls up well, he'll lead his team onto the MCG with fellow co-captain Kieren Jack, but if the veteran is ruled out, Swans general manager of football Tom Harley said his absence would be a huge blow. 

"He's obviously the co-captain of the footy club and clearly he provides some on-field output," Harley told sydneyswans.com.au. 

"But certainly the less tangible things that the supporters don't see, are what holds him in great stead at the footy club.

"He's obviously an extremely important and valuable player for our team, and we look forward to seeing how he progresses in the next couple of days." 

Key defender Aliir Aliir (knee) and NAB AFL Rising Star winner Callum Mills (hamstring) are the Swans' other big injury concerns this week, and Harley said the pair were progressing well, but like McVeigh, their availability will come down to Wednesday's closed session at the SCG. 

"His (Aliir's) spirits are good, he's obviously had a remarkable year," Harley said.

"It was disappointing he suffered the medial ligament strain against Geelong, but he's still a chance (to play).

"I know that he's put the work in around the clock to give himself that chance.

"Callum (Mills) is continuing to go through his rehab and he'll train fully, we expect, on Wednesday.

"Provided he gets through that he'll be available for selection.

"A bit like last week there are a few more hoops they need to go through."