Glory's finals hopes were extinguished on Saturday night as a first-half strike from Adam Taggart and a late own-goal from Jacob Pepper were not enough to prevent Brisbane Roar from running out 3-2 winners at nib Stadium.
The hosts went into the game requiring a combination of three points and Western Sydney failing to defeat Adelaide United in their meeting on Sunday in order to secure a top-six finish for the third season in a row.
But they were ultimately undone by a double from substitute Henrique and a Thomas Kristensen effort just before the break which means it will instead be the Queenslanders who clinch sixth spot if Wanderers are unable to down the Reds at ANZ Stadium.
A crowd of 9579 were treated to a night of high drama which included Diego Castro missing a 79th-minute penalty for the home side who had several other strong penalty appeals either turned down by the VAR or simply not referred by referee Peter Green.
Glory began brightly and deservedly took the lead on 24 minutes when Taggart calmly lobbed Jamie Young after the Roar 'keeper had rushed rashly out of his area and ended up in a tangle with Jack Hingert as the latter tried to deal with a long clearance from Liam Reddy.
By half time, however, the WA side found themselves trailing after Henrique took advantage of the hosts failing to clear a Fahid Ben Khalfallah free-kick by drilling a shot into the bottom corner and Kristensen then converted Matt McKay's cross from the left with a similarly clinical finish.
Seven minutes into the second half, 2-1 became 3-1 when the impressive Massimo Maccarone released Henrique and the Brazilian gave Reddy no chance with a low shot.
But to their credit, Glory proceeded to create a string of chances as they tried desperately to claw their way back into the contest, with Castro, Alex Grant, Joseph Mills and substitute Chris Harold all going close.
And Castro really should have handed his side a lifeline on 79 minutes when they were awarded a penalty after Young's needless push on Andy Keogh in the box.
Young, however, immediately made amends by blocking the Spaniard's spot-kick and although Pepper subsequently deflected Taggart's header into his own net to reduce the deficit on 86 minutes, it was too little, too late for Kenny Lowe's men as a frustrating season ended on a fittingly frustrating note.
Round 27 Hyundai A-League 2017/18 Season
Perth Glory 2 (Taggart 24', Pepper o.g. 86') Brisbane Roar FC 3 (Henrique 30', 52', Kristensen 41')
Half time: 1-2
nib Stadium, Perth
Referee: Peter Green
Perth Glory: 33.Liam REDDY (Gk), 2.Alex GRANT, 4.Shane LOWRY, 7.Joel CHIANESE (14.Chris HAROLD 70'), 8.Xavi TORRES (18.Andreu GUERAO 18') (20.Jake BRIMMER 70'), 9.Andy KEOGH (c), 16.Joseph MILLS, 17.Diego CASTRO, 22.Adam TAGGART, 23.Scott NEVILLE, 88.Neil KILKENNY
Substitutes not used: 13.Nick FEELY (Gk), 66.Dino DJULBIC
Yellow cards: Lowry, Keogh, Kilkenny
Red cards: None
Brisbane Roar: 21.Jamie YOUNG (Gk), 7.Thomas KRISTENSEN, 8.Jacob PEPPER, 9.Massimo MACCARONE (11.Corey GAMEIRO 87'), 10.Brett HOLMAN (33.Henrique SILVA 28') (16.Mitchell OXBORROW, 90'), 14.Fahid BEN KHALFALLAH, 17.Matt MCKAY (c), 19.Jack HINGERT, 22.Eric BAUTHEAC, 24.Connor O’TOOLE, 77.Ivan FRANJIC
Substitutes not used:2.Dane INGHAM, 31.Brendan WHITE (Gk),
Yellow cards: Pepper, Ben Khalfallah
Red cards: None