Geelong defender Tom Stewart is expected to miss close to a month of action after sustaining a suspected medial ligament injury during Friday's clash with Collingwood.

The All-Australian backman suffered the ailment early into his side's 22-point loss to the Magpies and was subbed out of the match in what was an early blow to Geelong's Round 1 plans.

Fellow defender Sam De Koning was also in hands of medical staff after an innocuous incident in the second quarter, however, the young backman was able to eventually return to the field despite the knee complaint.

Cats coach Chris Scott said on Friday night that Stewart is unlikely to feature in his side's Round 2 clash with Carlton, while De Koning's injury concern was minor.

"He was subbed off pretty quickly. I'd be surprised if he plays next week, but beyond that, it is hard to say," Scott said of Stewart.

"They [club doctors] don't think it is a really long-termer."

"[De Koning] was hampered, it was similar to a minor thing he had at training about three weeks ago. He bounced back really quickly from that, but he was certainly hampered," Scott said.

"Even with Stewart going out, there was no suggestion from our medical staff that there was a risk there putting him back on. We wouldn't take a risk; we would give up the four points before we'd put Sam De Koning at risk."

7 News reporter Mitch Cleary has revealed Stewart is likely facing 3-4 weeks on the sidelines, however the Cats are yet to learn the diagnosis of their vice-captain's injury.

Geelong are scheduled to face the Suns, Hawks and Eagles following their Round 2 matchup with Carlton.

The Cats weren't the only side to come away with an injury concern on Friday, with Collingwood defender Jeremy Howe forced to undergo surgery on a fractured forearm following a nasty incident during the third quarter of the win.

In a marking contest against Cat Tyson Stengle, Howe flew for a spoil before awkwardly landing on his left arm, with the veteran Magpie requiring medical treatment on the field.

Howe was stretchered off the MCG and soon placed in an ambulance before being taken to hospital.

Collingwood confirmed Howe went under the knife on Saturday and faces an extended stint on the sidelines.

“We are disappointed for Jeremy who suffered a compound fracture in his forearm during the game last night,” Collingwood football boss Graham Wright said in a club statement.

“He underwent scans last night and had surgery earlier today.

“Jeremy is a respected leader of our program who really puts his body on the line – our priority is making sure his welfare is supported through his recovery and we will do that.”

Collingwood has confirmed an update on Howe's likely return date will be provided in due course.

In a message to his Instagram account, Howe thanked fans for the overflowing support in the wake of the injury.

"No greater love and support than the fam," Howe wrote.

"I'll be back. Appreciate all the messages."

Collingwood will host Port Adelaide next weekend at the MCG following their strong outing against the Cats, while Geelong will enter next week's clash against Carlton as they chase their opening win of the season.