Glory suffered late heartache at Westpac Stadium on Saturday as a stoppage-time own-goal from the luckless Shane Lowry handed Wellington Phoenix a 2-1 victory.
A stunning first-half free-kick from Diego Castro had looked set to secure the visitors a share of the spoils, the Spaniard curling home his fourth goal in five games from the edge of the box after Sarpreet Singh had marked his starting debut by slamming home an equally impressive early opener for the hosts.
But Castro was unable to give his side the lead late on when, having been impeded in the box by Scott Galloway, his attempted 'Panenka' penalty failed to deceive home 'keeper Tando Velaphi who stood his ground and made the simplest of saves.
And that blow was compounded when Michael McGlinchey sent fellow-substitute Roy Krishna racing away down the left in the 91st minute and the Fijian's cross was inadvertently deflected past Liam Reddy by Lowry.
The defeat leaves Kenny Lowe's men in eighth place, seven points outside the finals places with seven games left to play, five of which are at home.
Glory received a brutal wake-up call when Singh put the hosts in front with the first meaningful effort of the game.
The youngster seized upon the opportunity to advance towards the edge of the box before unleashing a vicious shot that flew into the top corner.
That early drama was followed by a touching gesture from the Phoenix faithful who applauded throughout the 10th minute in tribute to former Glory midfielder Liam Miller who tragically passed away last week.
Liam Reddy then dealt comfortably with two free-kicks from Matthew Ridenton before Shane Lowry's fine block foiled Anrdija Kaludjerovic as he prepared to pull the trigger from close range on the half-hour mark.
But Glory were also starting to look more purposeful going forward and were duly rewarded via Castro's free-kick.
Having sent a previous range-finder over the bar, he was not to be denied a second time, calmly bending a low shot around the wall and beyond the diving Velaphi.
Lifted by that leveller, the visitors began the second half very much on the front foot and went close to taking the lead when Xavi Torres rose highest to meet a Neil Kilkenny corner only to see his downward header fly narrowly wide.
Moments later, substitute Joel Chianese looked to be in on goal after beating Thomas Doyle, but Velaphi was out quickly to save bravely at the winger's feet.
The game became increasingly stretched as it moved into its final quarter and seconds after Kaludjerovic had almost converted a Krishna cross, Chianese cut in and fired inches wide of Velaphi's far post at the other end.
It looked as though Glory's second-half pressure would finally be rewarded with nine minutes left when Galloway was adjudged to have blocked Castro illegally in the box.
But having dusted himself down and stepped up to take the spot-kick, Castro's decision to dink his effort proved to be the wrong one.
And it duly went from bad to worse for the WA side as Phoenix struck at the death to snatch all three points.
Hyundai A-League 2017/18 Season Round 20
Wellington Phoenix 2 (Singh 3', Lowry o.g. 90+1') Perth Glory 1 (Castro 36')
Westpac Stadium, Wellington
Referee: Alex King
Assistant Referee 1: David Walsh
Assistant Referee 2: Andrew Lindsay
Fourth Official: Adam Kersey
Video Assistant Referee: Chris Beath
Wellington Phoenix: 40.Tando VELAPHI (gk), 3.Scott GALLOWAY, 6.Dylan FOX, 7.Nathan BURNS (14.Alex RUFER 90+2'), 8.Matija LJUJIC, 9. Andrija KALUDJEROVIC, 17. Monty PATTERSON (21. Roy KRISHNA 46'), 18. Sarpreet SINGH (10.Michael MCGLINCHEY 68'), 19. Tom DOYLE, 22.Andrew DURANTE(c), 23.Matthew RIDENTON
Substitutes not used: 26.Liberato CACACE, 30.Keegan SMITH (gk)
Yellow cards: Ridenton, Durante
Red cards: None
Perth Glory: 33.Liam REDDY (Gk), 2.Alex GRANT, 4.Shane LOWRY, 6.Mitch NICHOLS, 8.Xavi TORRES, 9.Andy KEOGH (c), 16.Joseph MILLS, 17.Diego CASTRO, 23.Scott NEVILLE, 26.Jacob ITALIANO (7.Joel CHIANESE 57'), 88.Neil KILKENNY
Substitutes not used: 13.Nick FEELY (Gk), 18.Andreu GUERAO, 20.Jake BRIMMER, 66.Dino DJULBIC
Yellow cards: Grant, Lowry
Red cards: None