Sydney's breakthrough win of the season has been soured with news that Jarrad McVeigh and Will Hayward will both miss at least the next month of footy after being injured against Carlton on Saturday.
McVeigh strained his quad late in the match against the Blues at Marvel Stadium and is expected to be unavailable for the next 6-8 weeks.
Hayward had surgery on a broken jaw on Sunday and will spend the next four weeks on the sidelines.
The injuries are a massive blow for the Swans, who rely heavily on McVeigh's experience as a leader in defence, and Hayward's speed and goal sense at the other end.
Sydney coach John Longmire said while it's disappointing to lose the pair, he backed the club's depth ahead of Thursday night's clash with Melbourne at the SCG.
"Jarrad was really good again on the weekend with his organization down back and also his ball use, and Will is obviously an important goalkicker (for us) and has been since he came into the team," he said.
"He's a fantastic young player so it's disappointing to lose him.
"There's two players out of the team but there's a couple underneath that we're confident will be able to come in and fill those roles for us.
"A number of players played well in our reserves, so we'll discuss that at match committee."
The Swans will also be without veteran defender Heath Grundy for the third straight week, with Longmire conceding his back issue hasn't responded as quickly as the club had hoped it would.
Grundy had 11 possessions in the Swans' round one loss to the Western Bulldogs but pulled up sore and missed the past two matches.
"I think Heath will still be out for another couple of weeks," Longmire said.
"He's still not 100 per cent so we're going to take the time now to get it right.
"He's a few weeks away and we'll make sure we get his back right before he comes back and plays."
With Longmire needing to make at least two changes for the Demons clash, and McVeigh's experience sure to be missed, Kieren Jack looks likely to play his first senior game of the season.
Jack had off-season knee surgery but has increased his training over the past month and played some decent footy at reserves level.
The 31-year-old gathered 22 disposals and kicked a goal in the Swans' NEAFL win over Greater Western Sydney on Saturday, so could be an option to take Hayward's spot inside the forward 50.
Axed defender Colin O'Riordan has 26 possessions against the Giants across half back and looms as a logical replacement for McVeigh, while draftee James Rowbottom (31 touches and six tackles), James Rose (39 possessions and four goals) and Ryan Clarke (27 disposals) will also be in the mix at selection.