GREATER Western Sydney forward Jonathon Patton has torn the ACL in his right knee for the second time.
The 21-year-old Giant was injured when he landed awkwardly from a marking contest in the second quarter of Sunday's game against Melbourne at the MCG.
He left the ground immediately and was sent for scans, which confirmed the club's worst fears.
Patton previously injured his knee in round three, 2013 but looked to have made a successful comeback this year, playing 19 games and kicking 25 goals.
His teammate Dylan Shiel backed Patton to return bigger and better.
"I was right with him when he hurt his knee," Shiel said.
"Jonny's been terrific this year and had some pretty big setbacks in his first three years.
"I'm sure he'll rehab his knee the way he always has and he'll be back stronger than ever."
Patton clutched his knee in pain after the incident and took several moments to compose himself.
He walked to the bench and went straight down to the rooms to be examined.
He reappeared briefly to run along the boundary but then went back down to the rooms.
"He has had such a bad run with injuries and this year he has been so good for us and he is really leading the big man stakes," coach Leon Cameron said after the game, before the extent of the damage was known.
Patton was the No.1 selection in the 2011 NAB AFL Draft.
Phil Davis (concussion) and Callan Ward (calf) were also injured in the opening half of Sunday's match and played no further part.
Davis will be tested this week to assess if he's able to play Collingwood on Saturday, while Cameron said Ward's season was likely to be over.