COLLINGWOOD forward Dan McStay has been ruled out of the Toyota AFL Grand Final due to a knee injury.

McStay was substituted out of the Magpies' thrilling one-point win over Greater Western Sydney on Friday night and scans on Saturday confirmed a high-grade medial collateral ligament strain, ruling him out of the Grand Final.

It is a heartbreaking blow for McStay, who joined the Magpies from Brisbane ahead of this season, kicking 20 goals in 14 games.

"It's unfortunate to confirm that Dan has sustained a high-grade medial ligament injury during last night's preliminary final with an expected recovery time of six to eight weeks," Collingwood general manager of football Graham Wright said.

"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.

"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 had kicked two majors from five disposals against the Giants before being substituted.

He was on crutches as he headed for scans 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 said.

"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."

While Collingwood welcomed back Nick Daicos for the preliminary final, Taylor Adams (hamstring) missed and will be racing the clock to be fit for the Grand Final.

Tom Mitchell also underwent precautionary scans on a sore back, but is expected to be available for the Grand Final.

The Magpies will face the winner of Saturday's clash between Brisbane and Carlton in the decider.