As the rest of its rivals stumbled in the five-way race for first place, Phoenix - led by Australia striker Nathan Burns - fired as it overcame an early deficit to register an important victory on Sunday.
The match threatened to descend into farce in the second half as Brisbane's recent wild weather worsened, waterlogging the pitch to the point where short, simple passes were held up by large puddles.
Referee Alan Milliner was forced to officially abandon the game in the 73rd minute, with the result at the time standing to give Phoenix its first ever win at Suncorp Stadium in front of 10,075 brave fans.
An FFA match official explained: "It was the score at the time. If the game had been stopped before halftime it would have been a replay."
Brisbane's Andrija Kaluderovic put the home side ahead after just five minutes, poking in a cross from left-back Corey Brown to complete a clinical counter attack from Roar.
But it was a short-lived lead, as Wellington's in-form attack kept knocking at the door - and then kicked it down.
After a parade of chances, Michael McGlinchey finally restored parity for Phoenix after 15 minutes, although all the credit for the goal should go to Burns.
Cutting in from the right, Burns cut out five Brisbane defenders on a scything run before passing to McGlinchey, who made no mistake from point-blank range.
Then just moments before the halftime whistle, Burns pounced to put Wellington 2-1 up.
Fijian flyer Roy Krishna pulled the trigger from inside the box, but his shot cannoned off the right post and into the path of Burns, who had a wide-open goal at his mercy.
Phoenix is now four points ahead of Melbourne Victory, Sydney FC and Perth Glory, who are all tied in second place on 38 points.
The result also puts a dent in Brisbane's finals hopes, particularly after Melbourne City's surprise win over Sydney FC on Saturday.
Roar remains seventh, but is five points behind City and has the added challenge of an AFC Champions League campaign to contend with as the A-League season reaches the home stretch.
Phoenix coach Ernie Merrick - who was in charge of an A-League team for a 200th time - admits the A-League Premiers' Plate is now "very much" his team's to lose.
Merrick commented the second-half abandonment of the comeback victory over Roar took some of the gloss off the result, saying none of his players were celebrating winning in such fashion.
But not even south-east Queensland's unrelenting rain could have washed away what it means for the in-form Phoenix, who is zeroing in on its first ever piece of silverware.
"It's a credit to the boys," Merrick said.
"They're certainly enjoying it. They're full of confidence, it's such an important factor in a skilled sport.
"Brisbane Roar are a good team, they score goals, they're at home, and for us to come here and be winning at the end of the game like that is a tremendous credit, especially coming from 1-0 (down).
"The improvement's in every area of the team.
"It's first class and we're producing those results consistently, now playing against tough teams away from home."
Merrick also has arguably the A-League's most potent final third at his disposal.
Led by Burns, who took his season tally to 13.
"Nathan is becoming an even better player than I thought," Merrick said.
"One-on-one I think he could take just about anyone apart in this competition."