Goals from David Carney, Poland's Adrian Mierzejewski and Seb Ryall earned the points in a match marred by two red cards.
Sydney striker Matt Simon and Brisbane's Avram Papadoulous were both sent off in the second half following a VAR review of an incident in which the Greek defender spat at the forward.
The Newcastle Jets are in second place two points behind Sydney after putting four goals past 10-man Melbourne Victory in Newcastle.
New Zealand's Kosta Barbarouses marked his return from international duty with a fifth-minute opener for Victory before goals from Daniel Georgievski, Joey Champness and a brace from Andrew Nabbout.
Socceroo midfielder Mark Milligan was red-carded for a headbutt to Georgievski's chest.
There was another controversial VAR red card in Perth Glory's 3-1 away win over third-placed Melbourne City.
Osama Malik was sent off for a late studs-up tackle on Glory youngster Jacob Italiano.
Mitch Nichols, Spaniard Xavi Torres and Mitchell Mallia scored Glory's goals, with Scottish striker Ross McCormack netting City's only goal with a stunning free-kick.
Adelaide United climbed to fourth spot after a 2-0 win over Western Sydney, with Ryan Kitto grabbing a brace.
Daniel De Silva inspired Central Coast Mariners to an impressive 4-1 away win over bottom team Wellington Phoenix.
The skilful De Silva controlled play brilliantly from midfield, and along with the Dutch duo of Tom Hiariej and Wout Brama set up the sixth-placed Mariners' second win of the season.