Greater Western Sydney young gun Dylan Shiel will be battling to play again this AFL season after suffering a knee injury which is expected to sideline him for six to 12 weeks.

Dashing midfielder Shiel, 22, will undergo surgery on a torn lateral meniscus in his right knee and will have an exploratory arthroscope later this week to determine the extent of the injury.

The bad news came just a few hours after GWS announced they had re-signed another talented midfielder, Stephen Coniglio, to the end of 2017.

Their only top-notch youngster not yet locked away beyond this year is midfielder Adam Treloar.

The joy over successfully re-signing yet another of their young stars in Coniglio was tempered by the injury to arguably their most-dynamic and explosive midfielder.

Shiel, who recently signed a contract extension to 2017, came off the field in the second quarter of the Giants’ 35-point home victory on Sunday over St Kilda.

“Dylan has met with the knee surgeon today and it has been decided that we need to explore the extent of the damage arthroscopically,” Giants head of athletic performance David Joyce said.

“Depending on what we find will determine the surgical approach, which will then guide our return to performance timelines.

“This could be as little as six weeks and as long as three months depending on what we find.”

Injuries are threatening to derail the Giants’ attempts to make their maiden finals campaign, after breaking back into the top eight with the win over Saints.

Shiel joins a long-term casualty list which includes season-ending injures for ruckman Shane Mumford and key back Tim Mohr.

Two other key defenders, Joel Patfull (ribs) and co-captain Phil Davis (ankle), are expected to be out for one and four more weeks respectively.

Former No.2 draft pick Coniglio, 21, who logged a career-best 17 tackles on Sunday in his first game back from a shoulder injury, is the latest in a string of top-shelf youngsters to opt to stay with the Giants rather than be tempted to make a big-money move interstate.

He joins forwards Jeremy Cameron, Devon Smith and Will Hoskin-Elliott and Shiel, all of whom in recent months have committed to the Giants for two or more seasons beyond this year.

Davis also signed a contract extension earlier this season.

“I love the club and where we’re going,” Coniglio said.

“There’s plenty of hard work to come but I think we’re definitely on the right track.”