Kurt Tippett is out of Sydney's blockbuster clash with Port Adelaide and will have surgery on Tuesday to repair a knee injury.
The Swans say the star forward will miss two weeks after scans revealed a slight tear to the meniscus in his knee.
He will miss games against the Power and Richmond but the Swans are relieved his injury is not too serious.
Tippett missed the first seven games of the season with tendinitis in his right knee, however his latest injury is to his left knee.
"He's going to be missing the next two weeks. He's got a slight tear in his meniscus so he has a minor operation to trim the cartilage up a bit," said Swans coach John Longmire.
"He'll miss two games and should be right in three weeks' time.
"Gibbsy [Nathan Gibbs] our doctor suggested it was a not a bad result.
"Structurally his knee is fine."
Longmire said Tippett could resume weights training as early as Wednesday and start running again next week.
The injury is a blow to Sydney's forward line, which has been red hot in the past few weeks with Lance Franklin, Tippett and Adam Goodes all stationed inside their forward 50.
"He was a bit quiet on the weekend but he's been playing really well for us and doing a good job," Longmire said.
"If you look at the other possibilities that could have happened it's not necessarily a bad result.
"To come out missing just a couple of weeks, a bit of a trim and getting him back in a few weeks' time is a pretty good result."