Sanzar are expected to make their final decision on the location of the 15th Super franchise in October.
The ARU and Saru are the only unions left in the running for an extra place in the competition, after New Zealand pulled their Taranaki bid earlier in the week.
The ARU are working with three applicants from Melbourne for their bid, while Saru has endorsed the Port Elizabeth-based Southern Kings as their application.
Sanzar president Oregan Hoskins has suggested that the two applicants join forces to create a win-win situation for both parties, but it seems Melbourne and the Kings plan to go solo.
Both franchises have been invited by Sanzar to provide a formal application and a business plan for entry into the competition by 25 September.