What's a Prelim Final?

The lowest two ranked teams play each other, and the winner advances to the preliminary final. The winner of preliminary final gets through to the grand final. In this system, the top two teams are able to lose a match and still qualify for the Grand Final, this is referred to as a 'double chance'.

What comes first semi final or preliminary?

The top two seeds host their first two finals: the Qualifying Final and whatever final they play next (Preliminary Final if they win, Semi-Final if they lose).

What happens if AFL preliminary final is a draw?

If a drawn result is confirmed, then both teams will have a six-minute break before the game will resume with two three-minute halves. Teams will change ends at the end of the first three-minute half, but there will be no break, with play immediately resuming once the players are set.