Bruno Fornaroli's sixth goal in seven games was not enough to prevent Glory from suffering a first home defeat of the season as they went down 2-1 to league leaders Central Coast Mariners on Tuesday evening.
The visitors strode out to a 2-0 lead in the first half courtesy of an early close-range finish from Matt Simon and a powerful header from Marcos Urena and although Fornaroli nodded home a Kosuke Ota cross midway through the second half to set up a grandstand finish, Glory's sustained late pressure failed to produce an equaliser.
Richard Garcia made four changes to the side which started Friday's win over Brisbane Roar, handing Mason Tatafu a starting A-League debut and later giving fellow-Academy product Ciaran Bramwell his first taste of senior action off the bench.
And the Head Coach felt that there were plenty of positives to come out of what was keenly-contested game.
"Tonight, as much as the result was against us, I thought we played some good football and were actually on the front foot for most of it," he said.
"Again, we've got to tighten up the sloppiness at set-pieces and a few things defensively and just be a bit more focused on what we do without the ball.
"I made a few changes to try and rest a few bodies and we had six under-23s in the starting side, so when you're playing and relying on a lot of young guys, they're not always going to be firing on all cylinders.
"I still thought they played well and gave a good showing of themselves, but it definitely helps when those older guys come on and steady the ship a little bit.
"It's a tough schedule and we've got to be wary of how we manage the guys."
The Mariners took the lead with their first attack of the game, Stefan Nigro heading a half-cleared cross back into the box, Daniel Bouman flicking it on and Simon chesting the ball down with his first touch and drilling a shot past Tando Velaphi with his second.
There was another worrying for moment for Glory shortly after the opening goal when Urena burst through on goal, but a perfectly-timed tackle from Darryl Lachman prevented the Costa Rican from getting his shot away.
Glory's response came in the form of two dangerous crosses from Daniel Stynes and Nick Sullivan, both of which flashed across the face of goal, before Urena fired narrowly wide at the other end.
Carlo Armiento was next to try his luck as the sides continued to go toe-to-toe, fizzing a shot over the bar after breaking to the edge of the box and Fornaroli was similarly off-target seconds later.
And yet it was the Mariners who found a way through once again just before the break, Daniel De Silva's free-kick picking out Urena at the far post whose thumping header gave Velaphi no chance.
2-0 almost became 3-0 early in the second half, Simon meeting an Oliver Bozanic cross with a deft glancing header which drifted centimetres wide of the far post.
But spurred on by the introduction of Ota, Diego Castro, Andy Keogh and Brandon Wilson, Glory lifted the intensity and halved the arrears just after the hour-mark.
Ota delivered a fine cross into the box which eluded Keogh but sat up nicely for Fornaroli who steered his header past Mark Birighitti.
Keogh then just failed to make it 2-2, sending his header from a Dane Ingham cross just wide of the target and Daniel Stynes miscued with the goal gaping after fine approach work featuring Fornaroli and Castro.
Glory continued to pile on the pressure in the latter stages, but the Mariners also threatened on the break and De Silva twice went close to marking the eight-year anniversary of his Glory debut at the same venue with a goal.
The last chance of the night fell Glory's way, Keogh forcing a Neil Kilkenny corner goalward before a cluster of Mariners defenders prevented Fornaroli from applying the final touch.
Perth Glory 1 (Fornaroli 64') Central Coast Mariners 2 (Simon 6', Urena 40')
HBF Park, Perth
Referee: Daniel Elder
Perth Glory: 1.Tando VELAPHI (gk), 9.Bruno FORNAROLI, 16.Nick SULLIVAN (8.Kosuke OTA 58'), 18.Nick D'AGOSTINO (17.Diego CASTRO (C) 46'), 19.Callum Timmins (15.Brandon WILSON 58'), 20.Carlo ARMIENTO (10.Andy KEOGH 58'), 23.Dane INGHAM, 24.Daniel STYNES (38.Ciaran BRAMWELL 82'), 29.Darryl LACHMAN, 34.Mason TATAFU, 88.Neil KILKENNY
Substitutes not used: 6.Osama MALIK, 33.Liam REDDY (gk)
Yellow Cards: Timmins, Castro
Red Cards: None
Central Coast Mariners: 1.Mark BIRIGHITTI (gk), 4.Joshua NISBET, 5.Stefan NIGRO, 8.Oliver BOZANIC (c), 10.Daniel DESILVA (22.Michal JANOTA 90+1'), 11.Jack CLISBY, 12.Marcos UREÑA (29.Alou KUOL 62'), 14.Daniel BOUMAN (26.Jaden CASELLA 72'), 15.Kye ROWLES, 19.Matt SIMON, 21.Ruon TONGYIK
Substitutes not used: 3.Lewis MILLER, 20.Adam PEARCE (gk), 23.Dan HALL, 32.Max BALARD
Yellow Cards: Kuol
Red Cards: None