Collingwood have confirmed the fears that defender Reef McInnes' 2025 campaign is likely over after scans revealed an ACL setback for the swingman.

McInnes came from the field early into the opening term of Friday's six-point win over the Western Bulldogs following a marking contest that saw the Magpie land awkwardly.

The 22-year-old was assisted down to Collingwood's rooms for further inspection and didn't return to play, with tactical sub Ned Long injected into the game just moments after McInnes sustained the injury.

The Magpies initially believed McInnes had sustained a long-term setback, with scans on Saturday confirming the extent of the young tall's setback.

The Magpies have noted McInnes will be sidelined "indefinitely".

"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," Magpies football 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 Magpies are already without Ash Johnson (leg) and Tom Mitchell (foot) for extended periods due to injuries sustained this year, while Harvey Harrison is still working his way back from an ACL injury of his own.

Forward Brody Mihocek was ruled out of Round 2 due to a back issue, with coach Craig McRae revealing the veteran sharpshooter came into training hampered with a spasm.

"He got a back spasm yesterday," McRae said.

"He was in the squad, but he came in hobbling in. Which is most weeks for Brody (laughs).

"Potentially, in the past, we'd have put Brody out there because he's a guy that fights through that stuff. But we had Mason (Cox) ready to go and I thought Mason came into the team and played a role for us."

The Magpies will also monitor a facial injury to ruckman Mason Cox, who required stitches after a marking contest with Rory Lobb that saw the latter's fist make high contact with the Collingwood tall.

Magpies duo Finlay Macrae (shoulder) and Oleg Markov (calf) could be back in action in the coming weeks as they continue their rehabilitation.

Collingwood is scheduled to have a bye for Round 3 before a clash with Carlton at the MCG on Thursday, April 3.