WaiBOP knocked Wellington off the top of the table with a come-from-behind win at Cambridge yesterday.
All three goals came in the first half, with Luis Corrales giving Wellington a fifth-minute lead.
But Craig Wylie's deflected shot pulled WaiBOP level after the half-hour mark and Federico Marquez put the hostsahead right on halftime when put through one-on-one with Wellington keeper Michael O'Keeffe.
The capital side will rue a missed spot kick shortly before Marquez's strike, with WaiBOP keeper Danyon Drake saving Cole Peverley's effort.
The defeat, Wellington's second of the season, sees them drop to second behind defending champions Auckland City, who won 1-0 at Canterbury yesterday with a 55th-minute goal from Ryan De Vries.
The win lifts WaiBOP to fifth, behind Wanderers on goal average. Three points separates Canterbury in third from Waitakere in eighth.
"[We're] very happy with the performance," said WaiBOP assistant coach Paul Drake. "For us to get into the playoffs, we need to win every game. Next week, we go to Wanderers full of confidence."
Wellington coach Matt Calcott said his side never got into the game.
"If we had got that second goal just before halftime with the penalty, that might have changed things. But it wasn't a good performance from us, we were well beaten."
WaiBOP United 2 (Craig Wylie 38, Federico Marquez 45) Team Wellington 1 (Luis Corrales 5). Halftime: 2-1.
