GWS fear they have lost star ruck-forward Jonathon Patton for the rest of the AFL season with another anterior cruciate ligament injury.

Patton suffered the knee injury at training on Thursday morning and the Giants will know for sure on Friday after he undergoes scans.

He hurt his left knee in a marking contest and if Patton needs another knee reconstruction, it would be a major blow to the Giants’ finals hopes.

Patton underwent reconstructions in 2013 and 2014 to reconstruct his right ACL.

“The initial diagnosis for Jon doesn’t look positive however we’ll await the results of scans on Friday,” said Giants football manager Wayne Campbell.

The Giants have had rotten luck with injuries, but have won their past four games and are sixth on the ladder.

They are already without Toby Greene (foot) and Jeremy Cameron (suspension).

Patton, Cameron and Greene were their three leading goalkickers last season.

They head to Perth for Sunday’s clash with West Coast, whose forward line is also badly undermanned.

Josh Kennedy, Jack Darling and Mark LeCras are injured and Liam Ryan is unavailable.