The visitors soon found a goal through one Aaron Mooy free kick and almost had a second when the same player hit the crossbar with another. But Melbourne, for all their domination, rarely threatened Glen Moss' goal, such was the strength of the home side's rearguard.
And that quality is what would have confounded Merrick most of all. The Phoenix defended with a tenacity that has been missing far too often this season, frustrating a team who last week scored their 50th goal from just 20 matches.
While Melbourne would have briefly taken top of the table with a win, the Phoenix snuffed out the threat of Mooy, leading the competition in assists, and Bruno Fornaroli, on pace to break the A-League's scoring record.
That was only appropriate, given the game counted as captain Andrew Durante's 200th for the club, and rendered Merrick's attacking woes irrelevant. With Hamish Watson suspended and Blake Powell a late withdrawal courtesy of a hamstring complaint, the Phoenix played the entire match without a true striker.
But for a team missing a centre-forward, the hosts didn't treat that as an impediment in the opening stages. In fact, Fenton and Ridenton both performed rather convincing impressions of frontmen, making timely runs into the box and stealing onto a pair of quality crosses from Michael McGlinchey and Roly Bonevacia.
Two chances and two goals, but those expecting a similar success rate from their wild win over the Wanderers were soon issued a cruel dose of reality. Cruel, in particular, because Mooy's free kick took such a heavy deflection en route to goal that the midfielder was almost sheepish in his celebrations.
Having seen their lead halved, the Phoenix were unable to replicate anything resembling their early attacking raids. The game was subsequently played in only one half as the home side switched their focus to defending a narrow advantage.
Moss helped that task with a brilliant smothering save at the feet of Fornaroli and, mere moments later, Durante was called on intervene on the line as the Phoenix were left thankful for the halftime intervention.
But the pattern that had been established before the break continued throughout the second spell, although Wellington did at least enjoy the occasional foray into enemy territory. In the end, they need not have bothered, with another competition heavyweight knocked to the canvas by the ninth-placed upstarts.
Wellington Phoenix 2 (Fenton 12, Ridenton 15)
Melbourne City 1 (Mooy 19)
HT: 2-1
