Fremantle and West Coast have never met in a final.
That could easily change in 2015, and Sunday's derby will set expectations alight.
The Eagles would welcome a Derby final, says Sam Butler. http://t.co/lpxuWS3lgy— AFL (@AFL) August 13, 2015
But which roads actually lead to a derby final?
Road one: Dockers sail, Eagles dive
The most likely scenario is that Fremantle wins its first final and West Coast loses to Hawthorn, either in Perth or in Melbourne, depending on whether they finish second or third.
The Dockers would back themselves in against Sydney, Richmond, or the Bulldogs in Perth, earning a week's rest before playing a semi-final winner in the third week.
West Coast should be that semi-final winner. Even if they can't beat Hawthorn, the Eagles would start favourites at home against North Melbourne, Adelaide, Geelong, Richmond, or the Bulldogs.
That'd bring the two together in a preliminary final, with the Dockers holding the advantage of a week off.
Road two: Eagles fly, Dockers sink
The flipside scenario is that West Coast defeats Hawthorn, but the Dockers lose their first final against Richmond or some other team.
It looks unlikely that the Eagles will meet anyone other than the Hawks in their first final, but based on their brave performance last weekend, they are a chance of defeating the reigning premiers - especially in Perth.
Fremantle, on the other hand, lost to the Tigers in Perth earlier this year. The club also struggled to put down the Dogs, who are a sneaky chance to finish fourth.
The Dockers would start firm favourites in a Perth semi-final, setting up the same preliminary final date from the first road - but with West Coast having the extra week's rest.
Road three: Derby decider
The most tantalising prospect remains on the table: a WA-only grand final.
Fremantle and West Coast are both capable of defeating any opponent at home. They could both win qualifying finals, both take a week off, both win preliminary finals, and finally meet on the first Saturday in October.
The most likely wrecker for this plan is Hawthorn. Yet if the Eagles finish second and get a home final, they've got as much chance as knocking off the Hawks as any other team.
They'd also be doing Fremantle a favour, forcing the reigning premiers to play a semi-final while the Dockers are resting, making it easier for them to overcome Hawthorn and meet West Coast in the grand final.
Road four: First-up final
West Coast has a tricky run to finish 2015, with winnable-but-not-assured matches against Fremantle, the Bulldogs, and Adelaide.
If the Swans or the Tigers don't lose a match between this round and the finals, the Eagles could still drop to fourth. Fremantle, however, is well-entrenched in top spot.
The result? A derby qualifying final, with the (very) slim possibility of a repeat clash in the grand final.
Wrong road one: Eagles double-dive
It would stun everybody if Fremantle dropped two consecutive finals in Perth, but West Coast is on shakier ground.
The Eagles lack finals experience and could still face Hawthorn in Melbourne during the first week. A semi-final against Richmond, the Bulldogs, or North Melbourne - even in Perth - could threaten to tip them out in straight sets.
If that happens, the Dockers won't face the Eagles in a final, but will have a huge level of moral superiority.
Wrong road two: Perth teams plummet
Mathematically, if the two Perth teams lose their first finals, they could still make it to a WA-only grand final.
Realistically, it's impossible. Neither the Dockers nor the Eagles are guaranteed to win a qualifying final, with Hawthorn, Richmond, and the Bulldogs all threatening.
If both teams lose their first final, their paths will almost certainly never cross again in 2015.
Wrong road three: Rested but ruined
The most likely road to a WA-only grand final could also send the two Perth teams in opposite directions during week three.
If Fremantle and West Coast both win a qualifying final, they'll get a week off and face teams such as Hawthorn, Richmond, or Sydney in preliminary finals.
Despite the rest, the Dockers or Eagles (or both) could still drop this do-or-die match - especially against the all-conquering Hawks.
The thrilling prospect of a derby granny could get that close, but still slip away.
A derby final still looks a smidgen more likely than not.
Yet there are a lot of permutations out there, so make sure you enjoy Sunday's cross-town clash - just in case it's not repeated in 2015.