Rockdale City will host Sutherland next Wednesday night, July 29, in their deferred round 18 National Premier Leagues NSW Men’s 1 fixture.
Kick-off will be at 7.15pm.
The Suns and the Sharks are locked on 21 points, four behind fifth-placed Sydney United 58 but with a game in hand.
A loss in the derby would be fatal for either team's finals hopes.
The teams have played twice this season with Sutherland embarrassing the Suns in a 6-2 hammering at Seymour Shaw Park in April.
Rockdale gained revenge for that defeat when they eliminated Sutherland from the FFA Cup with a 3-0 victory at Ilinden.
Rockdale travel to Edensor Park to play Sydney United on Sunday, July 26, and Sutherland hosts Manly on Saturday night, July 25, at Seymour Shaw Park.