The Magpies defeated the minor premiers by nine points at Dial Park, 14.4 (88) to 11.13 (79), after being 14 points down at the final change.

Their final charge was one of two major comebacks for the game.

The Two Blues had started the game better, leading by 26 at half-time, before the Pies clawed their way back into the game to snatch the lead in the second quarter.

A Joel O'Donnell goal right before half-time gave Penguin a lead that grew to 20 points in the third term.

The final quarter saw multiple lead changes before Nick Milbourne sealed the deal for the Magpies with his fifth goal in the final minute of play.

"We knew it would be a tough contest and it was always going to be about the team that stayed in it the longest,'' Devonport coach Kurt Byard said post-game.

"But we are hungry and we know what finals footy is about. While we have been on the receiving end of it the last couple of years, we know you need to absorb pressure and take it and then get it on your terms and make the most of it when you get it on your terms and we did that today."

Claye Symmons, Ben Hawkes, Baynen Lowe and Quade Byard were the best for the Pies, while Dusten O'Neil, Joel O'Donnell, Jayden Van Essen and Dylan Bramich and Jack Templeton [four goals] led the charge for Penguin.

Penguin will now face the winner of Sunday's first semi-final between Wynyard and Burnie in next Saturday's preliminary final.

In a brilliant day for Devonport, its reserves and under 18s also qualified for grand finals.

The reserves defeated Penguin 10.7 (67) to 8.6 (54), while the under 18s defeated Burnie 16.16 (112) to 2.2 (14).