Striker David Williams returned to haunt former A-League club Melbourne City, scoring the only goal in a pulsating 1-0 win for the Phoenix in Wellington.
Williams' first-time shot in the fifth minute decided a willing contest on Saturday between two top-six clubs, with the home side dominating the first half but barely clinging on in the second.
Wellington's seventh win of the season further cements their path towards the playoffs, lifting them one point behind City, who are guaranteed to remain fourth by the end of round 16.
Williams, who played more than a century of matches for the City Blues, was arguably the game's best player with his work rate and incisive attacking forays.