Heading to Campbelltown Stadium amid an injury crisis and with just a single win in their past seven games, the Phoenix's three points came at a pivotal time, lifting them back within four points of the top six.
But after taking the lead via Jake Hollman's 15th-minute strike, just how the Bulls hadn't killed the game before Kazuki Nagasawa and Barbarouses put the visitors in front will haunt Bulls boss Mile Sterjovski, given the deluge of chances his side couldn't convert.
Sterjovski's side fired in 30 shots to nine throughout the game but a combination of wayward finishing and some inspired keeping from Kelly-Heald denied them, with the loss dropping Macarthur to sixth via a goals-scored tiebreaker with Sydney.
The 19-year-old keeper, playing just his second senior game, was credited with seven saves, including four in a frantic 40th-minute stretch in which his series of quickfire saves kept the deficit to one.
And the Bulls' profligacy was punished in the second half, first in the 65th minute when a superb backheel volley from Hideki Ishige set up Nagasawa to fire beyond Filip Kurto, netting his first ALM goal and tying the game up.
Not having had much to do to that point, the Polish keeper's night went from bad to worse four minutes later when he brought down Barbarouses and gave away a penalty, one the veteran attacker duly converted for both a century of ALM goals and the lead.
Desperate Macarthur pushed right to the end in search of a leveller but the song remained the same, with the Bulls either shooting wide or unable to beat Kelly-Heald.
