A breathtaking first half and a star turn from unlikely source Mason Cox inspired Collingwood to a shock 39-point preliminary final win over Richmond at the MCG on Friday night.

The Magpies booked their spot in next Saturday’s AFL grand final thanks to a near-perfect first half, in which they kicked 10 goals to two to set up an enthralling 15.7 (97) to 8.10 (58) victory.

Three of those 10 goals came from a 211cm Texan, with Collingwood’s American Pie also winning 15 disposals and taking 11 marks – eight of which were contested. It was a season-high for any player – and an unforgettable performance.

Loud chants of ‘USA, USA’ rang around the MCG both during and after the match, such was Cox’s dominance in the air, in a performance football legend Jason Dunstall described as “just ridiculous” on Fox Footy.

Steele Sidebottom was also sensational for the Magpies, gathering 41 disposals, as Richmond’s premiership defence and 22-match winning streak at the MCG came to a surprise end.

LISTEN. TO. THAT. ROAR. #AFLTigersPies pic.twitter.com/OXUxTNDUFo

— 7AFL (@7AFL) September 21, 2018

Collingwood, who finished 13th last year, led by as much as 53 points late in the second quarter.

Richmond produced some form of a fightback, with key forward Jack Riewoldt kicking five goals, but the closest the Tigers got was 21 points before the Magpies steadied.

Collingwood will now play either West Coast or Melbourne in the grand final as it seeks its first premiership since 2010.

“I’ve just got a bit of a different mindset to most of the boys,” Cox told the Seven Network afterwards.

“I don’t stress out too much about it. I just kind of focus on the little things … I think it was just a great team effort today.”

While Cox was being modest, Sidebottom and coach Nathan Buckley were quick to hail the 43-gamer, who had been criticised for two lacklustre finals performances this year.

“It was impressive to sit back and watch,” Sidebottom said.

“He takes a lot of pride in his performance. I think he’s been down a little bit over the last few weeks, but to see him come out and perform on such a big stage – that’s why we got him from the US.

Cox’s eight contested marks were one short of an all-time finals record. Photo: Getty

“Three years … he’s known the game. It’s a credit to himself, the people around him and the coaches … to teach him the game. I’m really proud of him.”

Buckley added that Cox “was huge – one of the better games in his career”.

The Collingwood coach also spoke with pride about his side’s “dynamic” first half.

Jordan de Goey was once again a key contributor for the Magpies, booting 4.2, while Taylor Adams (36 disposals), Jack Crisp (30 disposals, two goals) and Brodie Grundy (21 disposals, 56 hitouts, one goal) also starred for the victors.

Brownlow Medallist Dustin Martin was clearly hampered by his thigh problem, managing just six kicks and 19 disposals for the Tigers, and, crucially, no player really stepped up to fill the void in midfield.

Skipper Trent Cotchin won 25 disposals and had seven tackles and Dion Prestia (24 disposals) tried hard, but Riewoldt was the only real winner for Richmond on a dark night for the Tigers.

De Goey got things going for the Magpies with a clever snap from the boundary for the game’s first goal and Travis Varcoe, who was electric in the early stages, added another.

Riewoldt made amends for an early miss, though, to reduce the margin to four points.

The last seven minutes of the first term changed the complexion of the match, though, as Collingwood capitalised on its red-hot pressure to boot three late goals.

Collingwood’s pressure was outstanding. Photo: Getty

And the Magpies carried that surge of momentum into the second quarter, where they played near-perfect football and ran the Tigers ragged.

Richmond had no answer for Cox, who kicked three successive goals after a series of towering marks, and its plight was perhaps best summed up when 180cm midfielder Adams ran down Tigers ruckman Toby Nankervis on the half-forward flank.

And even when the Tigers enjoyed a brief spell of possession, they were unable to convert. Meanwhile, goals to Crisp and De Grey stretched Collingwood’s lead to a game-high 53 points.

Jack Higgins pulled a goal back on the stroke of half-time and to Richmond’s credit, they had a real go in the third quarter, kicking four goals to two as Riewoldt tried to inspire his side.

Collingwood then gave up the first two goals of the final term, leading to some nerves in a vocal pro-Magpies crowd.

But they needn’t have worried, with Adam Treloar’s snap and Grundy’s smart finish effectively settling the contest and sealing Collingwood’s finest win under Buckley.