Bottom side Central Coast held minor premiership contenders Sydney FC to a 1-1 draw in front of their own fans at Leichhardt Oval.
The Mariners took the lead against the run of play nine minutes before half-time when Adam le Fondre returned to the top of the A-League Golden Boot standings by netting the equaliser.
The Sky Blues will regard the game as two points dropped, despite having trailed. They are now 10 points behind leaders Perth Glory with eight games left.
Central Coast ended their four-match losing streak while Steve Corica's team have won just one of their past four fixtures.
Le Fondre now leads the goalscoring chart on his own again – with 13 for the season – one more than Perth's Andy Keogh and Roy Krishna of Wellington Pheonix.
He converted from the spot 14 minutes from time after Jem Karacan had been bundled over by substitute Alex Brosque in the box.
The home side couldn't go on and secure victory, with Brosque and Milos Ninkovic unable to take chances in the final three minutes.
They had started the game well and were unlucky not to take a 20th-minute lead through Ninkovic.
The midfielder fired a powerful shot against the post with Mariners keeper Ben Kennedy beaten and then, when he latched onto the rebound, his second effort was just wide.
Josh Brillante's volley was saved by Kennedy on the half-hour mark and the Sky Blues looked the more likely side to score only to fall behind when Aiden O'Neill fired in a shot that found the bottom corner past unsighted keeper Andrew Redmayne.
Corica said after he match: "We had about 14 or 15 shots, some one-on-ones, and hit the post so had plenty of good chances. It was not for the lack of trying and I can't take anything away from the boys' effort."
Sydney FC are 3/1 to win the Grand Final and 1/1 to win their next game against Wellington, who are 5/2 with the draw 13/5.