The Sydney Roosters and Cronulla Sharks will play at Allianz Stadium on Saturday, September 19, with the winner meeting The Dolphins in Brisbane.
The NRL has confirmed a second consecutive season of Friday-and-Sunday men's preliminary finals, prompting concerns about an uneven advantage.
The Roosters-Sharks winner faces The Dolphins at Suncorp Stadium on Friday, September 26, potentially giving the Roosters consecutive six-day turnarounds.
However, a Roosters victory would provide an additional 48 hours before the grand final compared with its eventual opponent.
Penrith will play the New Zealand Warriors or Newcastle Knights at Accor Stadium on Sunday, September 28.
That opponent will emerge from Sunday's Eden Park semi-final, beginning at 4:05pm AEST, after the Warriors' opening loss removed any feasible Friday fixture.
Penrith's Sunday start follows last year's break from the traditional Friday-Saturday format, when minor premiers Canberra opened the finals on Sunday.
The shorter-turnaround finalist will enter the October 4 decider, although Brisbane overcame that disadvantage against Melbourne last year.
In the NRLW, Sydney hosts one preliminary final on September 26, while Gold Coast hosts the other on September 27.