The Magpies stunned reigning premiers Richmond in Friday night's preliminary final, blowing them away in the second quarter and holding off their second-half challenge for a 39-point triumph.

The 15.7 (97) to 8.10 (58) win ended the Tigers' record 22-game winning streak at the MCG.

It rivals Carlton's famous 1999 win over Essendon as the biggest preliminary final upset in VFL/AFL history.

"We're not done yet, we've got another game to win," said Collingwood coach Nathan Buckley.

"We've really been strong on exploring ourselves, finding out what we're capable of, and we still don't know.

"We want to go and do that."

Giant American Pie Mason Cox was awesome, taking 11 marks and kicking three goals.

Jordan De Goey kicked four goals while midfielder Steele Sidebottom was best afield to continue his outstanding finals series.

Tigers key forward Jack Riewoldt was a lone hand with five goals.

Collingwood will join Essendon and Carlton with the most premierships if they win Saturday week's grand final.

That looked unthinkable 12 months ago, when Buckley survived massive pressure to keep his job.

Collingwood finished 13th last season, just as the Tigers climbed from the same ladder position in 2016 to break their premiership drought.

This is Collingwood's first finals series since 2013 and their first grand final since losing to Geelong in 2011, while their last premiership was celebrated in 2010.

The Magpies opponent will be the winner of Saturday's West Coast-Melbourne preliminary final in Perth.

Richmond kicked the first two goals of the last term, reducing the margin to a gettable 21 points.

But a goal to Adam Treloar relieved the pressure, while Richmond coach Damien Hardwick said Grundy's goal from a stoppage shortly after was the clincher.

Hardwick said what hurt the most was how badly Richmond played.

"I don't say this lightly - I can handle losing when you play a certain way," he said.

"What I'm disappointed in is the way we lost tonight, it was un-Richmond like.

"It wasn't through lack of effort and lack of intent, we just lost our way, which does happen from time to time and unfortunately happened in one of the most important games our guys will play."

Collingwood were on from the start, taking a 23-point lead at quarter time.

But no-one could have predicted what happened next.

Cox lit up the MCG, converting three strong marks into three massive goals in the opening 11 minutes of the second term

He blew the margin out to 42 points and it is surely the first time at any Australian sporting event where local supporters have chanted "USA, USA".

The Magpies kicked another three goals to add emphasis to the rout, extending their lead to a game-high 53 points.

Tigers star Dustin Martin, who was on light duties at training this week because of a corked thigh, clearly was not at full fitness and spent much of the first half playing deep in attack.

But Hardwick said there was no way Martin would have missed the game.

Hardwick also praised defender David Astbury, who had a quiet night after being ill during the week and going to hospital for an intravenous drip.

Australian Associated Press