EMERGING Collingwood defender Reef McInnes is likely to miss the remainder of the season after scans confirmed a ruptured anterior cruciate ligament on Saturday.

McInnes hobbled from the field in the opening stages of Friday night's thrilling six-point win over Footscray, after his right knee buckled following an awkward landing in a marking contest.

The 22-year-old went straight down into the rooms in the hands of medical staff and was immediately substituted out of the game.

McInnes managed 20 games across his first four seasons at the Magpies but had enjoyed a huge pre-season after switching to defence and looked to become a mainstay of Craig McRae's side.

"We are incredibly disappointed for Reef. He had an enormous summer and showed some really strong form in the pre-season and opening rounds of the season in a new defensive role," Collingwood footy manager Charlie Gardiner said.

"We were all hoping that he could have a consistent year and establish himself as regular part of our defensive unit but he is an outstanding person and we're confident he will bounce back from this latest setback. In the meantime, we will all rally around Reef and he will have our full support to ensure he makes a successful recovery."

The scans confirmed the Magpies' worst fears, with McRae revealing post-match that the club suspected the young defender had ruptured his ACL.

"It's devastating for the young man and his family and all of us," Collingwood coach Craig McRae said after the game.

"We put a lot of trust and hope in Reef that it was going to be a good season for him."

Collingwood heads into an early season bye with a 2-1 record following wins over Port Adelaide and the Bulldogs.