Victory pulled the Phoenix to within five points of the sixth and final playoff spot but, given their final three games are against teams inside the top four, they will need to be even better in the waning weeks of the regular season.
They will also need Barbarouses to replicate the form he showed tonight. The 37-cap All White made his intent known midway through the first half, grabbing the type of goal that, had he been scoring throughout the season, would have guaranteed an international call-up, turning Lachlan Jackson inside out before firing into the far corner.
And Barbarouses soon had a huge hand in doubling his side's lead, providing a pinpoint cross for Gui Finkler to head home for the Brazilian's third goal in as many games.
The 2-0 lead represented good reward for a bright start from the Phoenix, enjoying several more half-chances and regularly stretching the Jets' defence. The home side were far from flawless in the final third but rarely looked lost without the input of Fijian striker Roy Krishna.
Andrew Durante, on the other hand, could have been used in a backline that bent without breaking in the first half, doing well to snuff out Newcastle's attacks but probably allowing too many openings than their absent skipper would have liked.
While that continued in the second spell, Lewis Italiano proved more than capable in the absence of Glen Moss, making a few smart saves as the Phoenix eventually recorded their seventh clean sheet of the season.
And any defensive frailty was quickly rendered moot, with Matt Ridenton adding a third after Dylan Fox's header cannoned off the bar and Newcastle defender Jason Hoffman inadvertently wrapping up the result with a calamitous own goal.
There was still time for Roly Bonevacia to complete the rout and leave the watching All Whites with a challenge on their hands to get back into the team.
Wellington Phoenix 5 (K. Barbarouses 24, G. Finkler 37, M. Ridenton 49, own goal 65, R. Bonevacia 86)
Newcastle Jets 0
Halftime: 2-0
