The NRL could revive the concept of a finals double-header to extricate itself from a stadium juggling act which has western Sydney rivals Canterbury and Penrith on a collision course to meet in the city's east at Allianz Stadium.

While it is considered an outside chance at this stage, the NRL hasn't completely ruled out scheduling a qualifying final to be hosted by the Sharks alongside an elimination clash which will be staged by the Bulldogs or Panthers in the first finals double-header since 2013.

The outside-the-box thinking has been necessitated after the AFL locked down ANZ Stadium for the all-Sydney blockbuster between the Swans and Giants on Saturday afternoon during the first week of the finals for both codes.

It means the Olympic venue and Brisbane's Suncorp Stadium will be unavailable to the NRL on the day, with the Wallabies to host South Africa in the Rugby Championship clash in Brisbane later that night.