Western Sydney Wanderers and Melbourne Victory sit outside the top six after poor showings on Saturday, but Sydney FC are on the march.
Adam Le Fondre tormented Brisbane Roar while Western Sydney Wanderers' slump continued in the A-League.
Adelaide United let a lead slip at home to Wellington Phoenix, while Adam Le Fondre inspired Sydney FC against Western United.
Adelaide United are up to third in the A-League after beating Melbourne Victory 3-1, while second-placed Sydney FC won 3-1 at Perth Glory.
Sunday's A-League action brought more frustration for Brisbane Roar and Melbourne Victory, while Adelaide United had reason to celebrate.
Melbourne City moved top of the A-League on Sunday, while Central Coast Mariners registered their first win of the new season.
Western United suffered a first A-League loss despite a numerical advantage against Melbourne City, as Perth Glory beat Wellington Phoenix.
Goals from Australia internationals Rhyan Grant and Jamie Maclaren helped Sydney FC and Melbourne City to wins in Sunday's A-League action.
Wellington Phoenix have signed former Norwich City, Celtic and Sheffield Wednesday striker Gary Hooper as their marquee player in 2019-20.
Brisbane Roar claimed a first A-League point for Robbie Fowler in thrilling fashion, while Western United registered a maiden victory.