BEN McGlynn needs to have no doubt about his hamstring if he is to take his place in this week's Grand Final, according to a man who knows his predicament.

Simon Prestigiacomo was a late withdrawal from the team that contested Collingwood's 2010 Grand Finals after succumbing to a groin injury.

The former Magpie defender, who now works in the club's merchandising and licensing department, says McGlynn would need to be sure of himself if he was to commit to the cause just three weeks after injuring his hamstring against Adelaide.

"Whatever way he goes about it he has to be 100 per cent sure about it. There's no point going into it with 70 per cent of your mind thinking you can or can't play," Prestigiacomo told AFL.com.au.

"If he says he's right to play and he's 100 per cent then that's great, but if he's not, then as long as he knows he made the right decision by the team, that's all he can do."

Prestigiacomo said he remained certain he made the right decision when he pulled out on the morning of the game two years ago.

"It was more by the Saturday morning after training on it and trying to test it out again and again. By Friday afternoon it was getting worse and on the Saturday morning it made it a bit easier to know it wasn't 100 per cent," he said.

"As much as everyone says you're a part of it, when you're not a part of the 22, you don't feel a part of it. It's a tough decision and you feel for the guys."

Prestigiacomo said he sympathised with McGlynn and Hawthorn's Brent Guerra who ruled himself out of contention on Monday after failing to recover from a hamstring injury.

"It plays with your mind and it's a tough decision to make. It's the reason we all play - to play in Grand Finals," he said.

"To rule himself out so early he probably knew he was no chance. If he thought he was a slim chance, I'm sure he would have given himself until the last possible chance."

Luke Holmesby is a reporter for AFL Media. Follow him on Twitter - @AFL_Luke