Sydney Swans coach John Longmire today confirmed that Adam Goodes will miss the next six matches, with the three-time Club Champion set to undergo arthroscopic surgery on his injured right knee.

Goodes injured his knee in the round 13 clash against Port Adelaide and subsequently missed Friday night’s win over Carlton at the SCG.

While the initial diagnosis was for Goodes to miss just one week, the knee didn’t settle down as expected and will now require surgery.

“Unfortunately Adam Goodes won’t be coming back this week,” Longmire told the media on Monday afternoon.

“He is going in for an operation tomorrow and will probably be out for six weeks.

“We think it’s a bit of cartilage damage and they’re going in to find out exactly what it is tomorrow.”

Longmire said that it was a disappointing setback to lose a player of Goodes' experience, particularly in light of his recent form.

“Throughout his long career, Adam has shown an amazing ability to manage his body and recover from injuries," he said.

“He’s been playing really well for us before he got injured and I thought a few of those games that he played over a three or four week block were as good as he’d played for a long time.

“It’s just unfortunate for him and it’s unfortunate for us.

“He is obviously a great player and we look forward to him returning and playing a valuable role for us later in the year.

“On the positive side, we have introduced a number of new players to the team already this season, including five debutants, and to see them stand up when given their opportunity has been fantastic.”

Goodes’ knee injury is the second major setback he’s had in two seasons, after the star player missed six weeks with a quad injury in 2012.

After last year’s long stint without the Swans’ number 37, Longmire said he felt his team was well-prepared to cover the loss for the next six weeks.

“Last year I felt we were pretty competitive with him out and at some point in your evolution as a footy team you’ve got to make sure that you can cover some of your star players who have carried the load for a long time,” he said.

“Adam has been a star for this footy club for a long time and it’s been good to see the development of other players.

“We think that the balance of the team has meant that if an Adam Goodes misses we can still be competitive and that’s what it needs to be.

“You just can’t rely on Adam Goodes to win us games of footy and clearly over the next few weeks that won’t be the case.”

The Swans will also be without talented forward Lewis Jetta, who will miss this Sunday’s match against Melbourne at the MCG with shin soreness.

“Lewis Jetta won’t play,” Longmire said.

“His leg is still providing a bit of trouble and he’s still not able to do a full training session.

“We were hopeful that he’d be right to go this week, but he’s not playing.”

In positive injury news, Longmire also said that Sam Reid and ruckman Shane Mumford were a strong chance to return for this Sunday’s match.

“On the good side of the equation is that hopefully Mumford and Reid are both available for this week,” he said.

“Reidy has got to get through two training sessions. He trained today but he’s got two more to go, and hopefully he is OK and puts his hand up and is available for selection.

“Shane Mumford should be OK if he gets through the training session as well.”