Sydney FC got their hands on the Premiers' Plate but only after Western United had snatched a late victory.
Newcastle Jets finished their A-League campaign with an impressive victory over Wellington Phoenix, who go into the elimination finals.
Besart Berisha's Western United look to have done enough to reach the A-League Finals after a crucial win against Perth Glory.
English winger Craig Noone trudged off midway through the second half as Melbourne City lost control of their clash with Adelaide United.
Brisbane Roar rounded out their fixtures in the regular season with a 1-1 draw against table-topping Sydney FC on Monday.
Perth Glory succumbed to a disappointing A-League defeat, with Marco Rojas in fine form for Melbourne Victory.
Western Sydney Wanderers valiantly fought back to level terms from 3-0 down but ended up falling to a late defeat against Western United.
Adelaide United will need favours from elsewhere if they are to be certain of a place in the A-League Finals.
Scott McDonald put Brisbane Roar ahead after the hour but Gary Hooper ensured a 1-1 draw for Wellington Phoenix in the A-League.
Neil Kilkenny and James Meredith scored late to boost Perth Glory's top-six chances, while all-but ending Western Sydney Wanderers' hopes.