The Mariners will hold onto a two-point advantage after they claimed just their second win in eight games by edging Adelaide United 1-0.
Teenage striker Bernie Ibini grabbed the most important goal of his young career on 47 minutes to claim the win at Bluetongue Stadium.
That ensured attention moved down the road to Hunter Stadium where the Roar kept alive their hopes with a 2-1 win over the Newcastle Jets.
Mitch Nichols claimed the important win with an 81st-minute penalty after Henrique had earlier seen a spot-kick saved for the reigning champions.
Besart Berisha fired the Roar ahead on 14 minutes but a delightful Ali Abbas free-kick in the 40th minute levelled matters.
Henrique saw the Roar's first penalty saved by Ben Kennedy on 54 minutes but, when Jets defender Tiago Calvano again gave away a second spot-kick late on, Nichols made no mistake.
The Roar may now fancy their chances of pinching the Plate with a final-round meeting with rock-bottom Gold Coast United while the Mariners face a tricky away date at the Wellington Phoenix.
In Saturday's other game, a second-half brace from Shannon Cole helped Sydney FC claw back from a 2-0 half-time deficit to clinch a draw with Melbourne Heart at AAMI Park.
The result means the Heart qualify for their first finals tilt while the Sky Blues have to win next week against the Jets to make the top six.
Mate Dugandzic (31) and Eli Babalj (36) had fired the Heart into their lead before Cole stole a point with goals on 66 and 77 minutes.