Rockdale City have slipped outside the NPL 1 top five after a deflating 5-1 defeat to APIA Leichhardt on Sunday.
The Suns have now lost four of their last five games to sit sixth on for and against behind Manly United.
The Tigers thrashed Rockdale 4-0 in round five and scored another five goals against the Suns at the Ilinden Sports Centre to keep themselves in second place behind Wollongong.
Rockdale led thanks to an Alec Urosevski strike just after the half hour mark. But Sean Symons pounced to level the scores three minutes before half-time after the Suns had failed to clear their lines.
Veteran Franco Parisi and Chris Payne scored doubles after the break to give the visitors a commanding victory.
The Suns will look to bounce back when they take on Sydney Olympic at Belmore Sports Ground on Sunday.
It shapes as an important game for Rockdale, with Olympic just three points behind the Suns but with a far superior for and against.
Meanwhile, St George FC will learn their FFA Cup round of 32 fate on Wednesday night.
The draw for the national round of the competition will be made as A-League teams join the tournament.
St George downed NPL 1 giants APIA Leichhardt, who eliminated then A-League champions Melbourne Victory last season, 1-0 in the sixth preliminary round at Caringbah.
Saints then beat NPL 3 side Dulwich Hill 4-0 in the seventh preliminary round to advance to the national competition for the first time.