THE SYDNEY Swans will be without influential midfielder Jude Bolton up until the AFL finals, but it was a medical diagnosis full of good news for the high-flying club.

Coach John Longmire feared the worst when he saw the vision of Bolton hyper-extending his knee in the third quarter of Sunday's victory over Carlton at Etihad Stadium.

Scans have shown a partial tear of both his anterior and posterior cruciate ligaments, but not the full tear that would have required surgery and ruled him out until well into 2013.

"We're expecting at this point he will probably be about a month," Longmire told reporters on Monday.

"Late last night we were probably fearing the worst, especially after I got to see the vision - I didn't think it looked too good.

"So I went home last night thinking the worst and woke up this morning with relative good news that we can still see Jude Bolton playing for us hopefully this year.

"When you get the full tear, there's no ifs, buts or maybes, you have to get surgery.

"The first thing [club doctor Nathan Gibbs] said to me was 'There's no surgery required', so that was a big positive from our point of view."

Earlier in the day Bolton had tweeted he would be out for two to three weeks - this from a man who has missed just 16 games since making his debut in round 12, 1999.

It means he will be left stranded temporarily on 297 career matches.

Longmire quickly swatted away a cheeky suggestion Bolton could now bring up the 300-game mark in a preliminary or Grand Final, but was confident his side would be able to cope with the veteran's absence.

The Swans have already been without Adam Goodes, Shane Mumford, Lewis Roberts-Thomson and Sam Reid at times and are riding a nine-game winning streak and sit on 15-3 for the season.

"He's a really good player, but we've missed really good players throughout this year and been able to cope," Longmire said.

"It's just another challenge.

"We've got a number of inside midfielders that can play certain roles, the challenge is to do it as good as Jude."

Ruckman Mike Pyke rolled an ankle against the Blues and will be monitored during the week.

The Swans face a huge task taking on Collingwood at ANZ Stadium on Saturday, a team they haven't beaten in 10 attempts dating back to 2006.

But they did get within one goal last year and Longmire is hoping to see how far his side has improved.

He also believes the midfield will be a key, putting more of a spotlight on the loss of Bolton.

"You could probably roll off about seven or eight of Collingwood's [elite] midfielders pretty easily and that's a massive part of where the game will be decided this week," he said.

"Collingwood's midfielders are some of the most elite and talented midfielders in the competition.

"I think ours have been in pretty reasonable form, but we'll find out how good the form has been against Collingwood this week.

"It's an important game for us."

James Dampney covers Sydney AFL news for AFL.com.au. Follow him on Twitter: @AFL_JD