COLLINGWOOD defender Lynden Dunn is still in shock as he comes to terms with spending another season on the sidelines after rupturing the ACL in his left knee in his comeback game at VFL level.

The 31-year-old backman missed the second half of last season after suffering the same injury in round 15.

In Thursday night's VFL practice match against Richmond at Punt Road Oval, played ahead of the Tigers-Pies blockbuster at the MCG, Dunn twisted awkwardly and then hobbled from the field in the hands of a trainer.

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He played no further part in the game as Collingwood's medical personnel tested the same knee as last year's injury to determine the extent of the damage.

"We’re very disappointed for Lynden, who has been so meticulous in his approach to his rehabilitation and training since his first ACL injury last year," Collingwood general manager of Geoff Walsh said. 

"Lynden will have surgery next week and begin the recovery process with the entire Collingwood family behind him. 

"To be at the AFL match afterwards, supporting his teammates, is an insight into the leader and clubman Lynden is. We know he’ll continue to be part of our journey in 2019.”

Dunn was resigned to the results showing yet another ACL rupture when he spoke to the media on Friday morning.

"I knew I’d done something," Dunn said.

"It’s not positive. I certainly felt something shift in my knee. It felt different to my first one. It was a bit of unknown the first time, yesterday felt like probably what [doing] a knee feels like. I’m not very confident [scans] are going to go well, we’re pretty sure it is what it is. I’m more in shock than anything."

While it can take some players up to 12 months to fully rehabilitate a knee and return to the field, Dunn's comeback on Thursday came just nine months after the injury occurred.

But the Magpies defender insists he didn’t rush his return, and is trying to remain positive as he embarks on yet another rehab journey.

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"I felt strong. I felt physically and mentally ready," he said.

"I couldn’t have done anything more with my rehab, we didn’t cut any corners. I wouldn’t change anything , it’s just one of those things.

"There’s people in the world with bigger problems. It’s not ideal for me, but the sun came up this morning, I’ve got other things in my life going on. It’s certainly not ideal but I’ll have to deal with it, move on and hopefully rehab it right and get back out there."

Dunn spoke with his surgeon on Thursday night and has already ruled out LARS surgery as an option.

He said he would continue to assess all his options and is open to a variety of different treatments but conceded a traditional knee reconstruction was the most likely outcome.

Teammate Tyson Goldsack, who last year made a miraculous recovery from an ACL injury and returned in time for Collingwood’s finals campaign, said he was gutted for Dunn.

"It’s pretty shocking," Goldsack said. 

"You don’t want to see it happen to someone once, let alone twice and then to come back. It’s more the mountain of work we’ve seen him do in the lead up. It’s really sad."

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Collingwood coach Nathan Buckley, speaking after the Magpies' win over Richmond, said he did not relay the news to his team ahead of its game, but added the early diagnosis didn't look promising.

"We didn't mention it pre-game, but we believe that it filtered through to the boys in varying stages in the half an hour before we took the field," he said.

"The prognosis is not good, but we'll obviously wait for scans on that, but 'Dunny' is a much-loved member of our football club because he's a member of our football club. He gives so much of himself and he has contributed so much since coming across from Melbourne.

"We really value what he brings to the table on and off the field, and his teammates will rally around him regardless of what the final scan shows."

Dunn is in his third season at Collingwood after 11 years and 165 games at Melbourne.