SPECIFIC plans for round four of the NAB Cup remain up in the air, with the AFL still considering dozens of fixture possibilities.

The NAB Cup Grand Final could be played in one of three cities, with Melbourne's Etihad Stadium, Adelaide's AAMI Stadium and Perth's Patersons Stadium still in the mix.

The location of the Grand Final is completely at the AFL's discretion.  All eight matches will be played in capital city locations.

Venue possibilities for the fourth round of the NAB Cup are Etihad Stadium, Simonds Stadium, Blacktown International Sportspark, AAMI Stadium, Patersons Stadium, Metricon Stadium, Manuka Oval and VISY Park.

"No regional venues will be used and where possible AFL venues [will be used]," League spokesman Patrick Keane said. 

Match-ups are expected to become clear on Saturday afternoon, but the League says it won't discuss hypotheticals with so many scenarios still possible.

Adelaide and West Coast are the front-runners to battle it out for the pre-season trophy, as both are undefeated on 12 points.

Mathematically another eight teams are possible grand finalists, but under the new NAB Cup format, percentage counts.

Hawthorn (194.12), Fremantle (146.15) and Geelong (137.29) are next in line for a Grand Final berth, all on eight points.