Waitakere had the better of the opening half and spurned a pair of good opportunities in front of the 3,000-strong crowd. But the class of the fulltime professionals from the Phoenix began to show in the second period and their more clinical finishing proved the difference between the two sides.
Missing many of their regulars, Waitakere fielded a makeshift line-up that included the likes of Bay Olympic pair Ross McKenzie and Ryan Elder, along with Three Kings United striker Sam Margetts, one of the leading scorers in the local northern premier league competition.
Margetts had a glorious chance to make a name for himself in the 20th minute when he was put in on goal after Ryan Baldachino cut in from the left and played the ball into his path. But the youngster failed to keep his composure and fired his effort wide.
Waitakere were made to pay for that miss moments later when Phoenix playmaker Daniel was bundled over in the box. Former English professional Paul Ifill took responsibility from the spot and made no mistake, dispatching his effort just beyond the reach of Waitakere goalkeeper Andy Ralph.
But the amateurs were back on level terms by the halftime whistle, Martin Bullock swinging over a free kick for midfielder Chris Bale to glance a neat header home.
Waitakere could even have taken a 2-1 lead with them into the sheds but McKenzie could not make the most of a perfect opportunity after some impressive build-up play.
Coach Neil Emblen cleared the substitutes bench at halftime, giving only a couple of players a second chance to match their more illustrious opponents.
The new arrivals were obviously going to take some time to get into the rhythm of the match and, by the time they were up to speed, the Phoenix had already nudged themselves ahead through Mirjan Pavlovic, who had replaced goalscorer Ifill with around ten minutes remaining in the first half.
The West Aucklanders could have drawn level once more but were again left to rue their lack of accuracy in front of goal, Keegan Linderboom becoming the guilty party this time by firing his shot well wide of the target.
Pavlovic wrapped up the scoring at 3-1 when he was left unmarked in a dangerous position in front of goal.