Collingwood have ruled Daniel McStay out of the AFL Grand Final after scans confirmed the key forward suffered a knee injury.
McStay kicked two vital goals in the Magpies' thrilling one-point preliminary-final win -- 8.10 (58) to 8.9 (57) -- over GWS on Friday night before hurting his right knee during the third quarter.
McStay cut a despondent figure amid otherwise jubilant scenes in the Collingwood change rooms after the match.
Scans on Saturday revealed the 28-year-old suffered a high-grade medial strain in his knee, ruling him out for up to eight weeks.
"Dan has been an important part of our season this year and played an integral role in the last night's victory against the Giants," Magpies football boss Graham Wright said.
"We are all disappointed for Dan to miss the grand final, but we will all rally around him, and he will continue to be a part of the team's preparations for the week ahead."
McStay was on crutches as he headed for scans near Collingwood's headquarters on Saturday.
"It's pretty scary so close to playing in a granny and it might have been taken away from me, so we will wait and see," he told reporters on Saturday.
"Obviously for myself, it's a bit of mixed emotions but I'm just incredibly proud of the boys and the way they played last night and the way they were able to shut the game down.
Magpies coach Craig McRae said it was difficult to see McStay in that position.
"I don't want to put a definite decision on it but I think he might be unlucky to miss out. We'll wait and see," McRae said on Friday night.
"At the moment, until you really know, you put your arms around him and show love and support as best you can."
McStay moved from Brisbane as a free agent at the end of last year and missed three months of his first season at Collingwood with an injured finger, which was operated on and then became infected.
He returned in round 18 and has kicked multiple goals in eight of the Magpies' last nine matches, taking his tally to 20 in 14 appearances in the black and white.
Collingwood vice-captain Taylor Adams is also in significant doubt for the season decider after sitting out the preliminary final with a hamstring injury.
"That's going to be a watch the clock," McRae said.
"I think every second is going to be needed. We'll push it to the line and see how we go."
Wright confirmed midfielder Tom Mitchell had been sent for precautionary scans on a sore back but expects the 2018 Brownlow medallist to be available for next Saturday's Grand Final.