GREATER Western Sydney breathed a sigh of relief when Stephen Coniglio escaped a serious knee injury on Sunday, but that news has been soured with young ruckman Matt Flynn requiring a knee reconstruction.

Flynn, 21, ruptured his ACL in the Giants' win over NT Thunder in Darwin on Saturday night and just like they had with Coniglio, Giants officials had their fingers crossed that he'd avoided major damage.

However, scans on Monday revealed the worst.

Flynn in action during this year's JLT Community Series. Picture: AFL Photos

The promising big man has been developed slowly at reserves level but made some big strides this year, his fourth season with the club.

A graduate of the GWS academy, Flynn had shown outstanding recent form and was close to making his debut when Shane Mumford was ruled out of the Giants' round 16 clash with Brisbane, before the experience of Dawson Simpson was preferred. 

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"It's devastating for 'Flynny'," Giants footy boss Wayne Campbell told gwsgiants.com.au.

"He's developed each year, each month and each game really, since he's been at the football club and had been really close to senior selection.

"He stepped on the back of Jye Caldwell's leg and hyperextended his knee.

"A bit like Stephen we were hopeful (that he'd escaped an ACL tear) given the diagnosis of our doctors on Saturday night but scans showed a tear.

"We're not having a great run at the moment, but we'll rally around 'Flynny' and the rest of our boys and get on with it."

In further disappointing news for GWS, small forward Zac Langdon has had surgery on a syndesmosis injury he suffered against the Lions.

He's expected to miss at least eight weeks, meaning he's not likely to play again this season unless the Giants can play multiple finals.

Langdon was impressive as a mature-aged recruit last season, kicking 21 goals from his 21 games, but has made just three appearances this year because of a foot injury.

Zac Langdon looks set to miss the remainder of the season. Picture: AFL Photos