MELBOURNE will play off for a grand new flag for the first time, defeating reigning premier Brisbane by four points in a preliminary final at the MCG.

Alyssa Bannan was the star of the show, booting three goals in a match-winning turn, with her pace and height too much for the Lions to counter in the 5.3 (33) to 4.5 (29) result.

Brisbane defender Shannon Campbell kicked a rare goal with six minutes remaining to cut the margin to 10 points in the fourth, with Greta Bodey following up with 36 seconds remaining.

Then at the worst possible moment, the Lions conceded a 5-6-5 free kick, handing the ball back to Melbourne at the centre bounce. While Brisbane eventually got the ball into its forward 50, the Demons' pressure ensured it would earn the win.

DEMONS v LIONS Full match coverage and stats

The constantly drizzly conditions in the first quarter favoured Brisbane's high-pressure game, but as the weather dried up, Melbourne's sharp kicking skills and neat hands around the stoppage came to the fore.

Melbourne kicked three stunning goals in the third term to earn the match-winning break:  Bannan (streaming away from Bre Koenen), Lauren Pearce (snatched out of the ruck) and Eliza McNamara (a sharp, low tumbler) leading to a nine-point lead.

Veteran Karen Paxman was extraordinary in game No.50, comprehensively shutting down Brisbane star winger Orla O'Dwyer, while Eliza McNamara and Sophie Conway were locked in an intriguing battle on the opposite side of the ground.

After Tayla Harris' star turn against the shorter Campbell the last time they met, Phoebe Monahan took responsibility for the spearhead and shut her out of the game, albeit in conditions not overly suited to talls.

Dakota Davidson could come under MRO scrutiny for an unusual wrestling-style lifting tackle on Lily Mithen, while Lulu Pullar left the ground with trainers after a low smother by Shelley Scott.

MELBOURNE     0.0     1.2     4.2    5.3  (33)
BRISBANE         0.1     1.2     2.3    4.5  (29)

GOALS
Melbourne: Bannan 3, L. Pearce, McNamara
Brisbane: Smith, Davidson, Campbell, Bodey

BEST 
Melbourne: Paxman, Bannan, McNamara, L. Pearce, Mithen
Brisbane: Bates, Dawes, C. Svarc, Grider, Hickie

INJURIES 
Melbourne: Nil
Brisbane: Pullar (lower leg)

Reports: Nil 

Crowd: 6,436 at the MCG