A late goal from substitute Blake Powell condemned Glory to a 1-0 defeat against Central Coast Mariners in Gosford on Sunday.
The injury-ravaged visitors had looked set to secure a battling point until the former Sydney FC man rifled home a cut-back from Danny De Silva with just 12 minutes left.
Kenny Lowe's side, however, showed plenty of resolve throughout and were unfortunate not to secure a share of the spoils.
In what was a gritty, arm-wrestle of a contest played out in warm conditions, Mitch Nichols came closest to finding the net for Glory when he was denied by home 'keeper Ben Kennedy on the stroke of half time.
And in terms of other positives for the WA side, there were lively cameos off the bench from Mitch Mallia and 19-year-old debutant, Yagoub Mustafa, plus some sterling defensive work from the likes of Alex Grant and Shane Lowry.
Ultimately, however, it was Powell's emphatic finish, which came only seconds after the striker had replaced Kwabena Appiah, that proved the difference between the two sides.
Goalmouth action was thin on the ground during a rather cagey first half, with the hosts' best effort coming on 28 minutes when Appiah's diving header from a Jake McGing cross was parried by Liam Reddy.
Nichols, meanwhile, was involved in both of Glory's best moments before the break, dragging a low shot wide having been picked out by Chris Harold and then working another shooting opportunity, only to see Kennedy stick out a left boot to block his angled strike.
Having finished the first half on the front, the visitors began the second in similar fashion as seven minutes in, Jeremy Walker's cross was cleared only as far as Harold,but the winger's goalbound effort was deflected wide by Alan Baro.
Powell's dramatic intervention then stunned Glory, however and although Mallia threatened late on, the Mariners defence held firm to secure what was their third win in the last four games.
Central Coast Mariners 1 (Powell 78') Perth Glory 0
Central Coast Stadium, Gosford
Referee: Kris Griffiths-Jones
Assistant Referee 1: Lance Greenshields
Assistant Referee 2: James Tesoriero
Fourth Official: Shaun Evans
Video Assistant Referee: Strebre Delovski
Central Coast Mariners: 1.Ben KENNEDY (gk), 4.Jake McGING, 5.Antony GOLEC, 6.Tom HIARIEJ, 7.Andrew HOOLE, 10.Daniel De SILVA (12.Trent BUHAGIAR 90+1'), 11.Connor PAIN, 13.Kwabena APPIAH (8.Blake POWELL 77'), 15.Alan BARO (c), 21.Kye ROWLES (16. Liam ROSE 60'), 23.Wout BRAMA
Substitutes not used: 14.Adam BERRY, 18.Thomas GLOVER (gk)
Yellow cards: Rowles 55', McGing 66', Powell 90+2'
Red cards: None
Perth Glory: 33.Liam REDDY (gk), 2.Alex GRANT, 4.Shane LOWRY (c), 6.Mitch NICHOLS, 8.Xavi TORRES,14.Chris HAROLD (11. Mitch MALLIA 72'), 15.Brandon WILSON (20.Jake BRIMMER 84'), 16.Joseph MILLS, 19.Joe KNOWLES (34.Yagoub MUSTAFA 86'), 26.Jacob ITALIANO, 29.Jeremy WALKER
Substitutes not used: 5.Jacob POSCOLIERO, 13. Nick FEELY (gk)
Yellow cards: Grant 90+3'
Red cards: None