Sydney have bluntly rated Jarrad McVeigh's calf muscle injury as nasty and are unsure when he will return to the AFL.
The Swans revealed the severity of McVeigh's injury on Tuesday, as young star Isaac Heeney was also ruled out for the start of the season with glandular fever.
McVeigh injured his calf at training last week and it was already thought that the former captain would miss round one for the third year in a row.
But the injury involves tendon damage and the Swans now think he will be sidelined for a couple of early-season matches at least.
"It is a bit of a nasty calf and he won't be playing at the start of the season," manager of football Tom Harley said.
"An exact return date, it's a bit hard to pin down, but he won't be playing in the first couple of weeks."
Utility Gary Rohan (back/hamstring) and small forward Tom Papley (knee/shin) will also not play in the round-one match against Port Adelaide.
Former co-captain Kieren Jack and possibly key defender Aliir Aliir are set to have their first hit-out of the campaign in Sydney's final pre-season match against St Kilda in Albury on Sunday.
Coach John Longmire is happy with the progress of key forwards Sam Reid and Lance Franklin, as well as ruckman Sam Naismith, all of whom played in last Friday's pre-season game against GWS.
"Reidy missed all of last year but he's had a really good pre-season this year and Lance and Sammy Naismith had off-season surgery, but have bounced back really well and are in good shape," Longmire said.