A young PGFC Academy First Team was edged out by 3-2 by Sorrento in Saturday's NPL WA clash at Percy Doyle Reserve.
Alex Morgan gave the hosts the lead on 25 minutes, but Alessandro Circati levelled for Glory two minutes later.
Cameron Teece then restored Sorrento's lead early in the second half before Jordan Roberts added a third and although Jaidon Seldon subsequently reduced the arrears and Glory dominated the latter stages, they were ultimately unable to grab a share of the spoils.
With a host of players unavailable due to first-team or international duties, Head Coach Richard Garcia was forced to ring the changes, but he felt that the team's performance served to illustrate the strength in depth of the club's Academy programme.
"Again, mistakes cost us," he said, "and when we make them, we must learn from them.
"We need to concentrate harder on not making silly errors that give teams the advantage.
"We played some very good stuff, but we need to maintain that for a full game.
"It was great for the players to get the experience of being in the senior squad against Manchester United, but the players that came in did a good job and showed glimpses of what they are capable of.
"We had plenty of possession today, but failed to capitalise, which is something we will need to improve ahead of our home game against ECU Joondalup next weekend."
Glory began Saturday's early kick-off brightly and thought they had earned a penalty seven minutes in.
A fine through-ball from Abias Bukuru sent Luke Salmon racing goalward and as he cut past Sorrento defender Scott Robinson, the Glory striker looked like he was brought down, but referee Shane Skinner waved away the penalty appeals.
Sorrento, meanwhile, went close themselves on 20 minutes when a corner was not cleared and Jack Salter’s shot on the turn flashed centimetres wide of the post.
Moments later Jackson Lee did well to keep out David Stokoe’s header, but from the resulting corner, the hosts hit the front as Alex Morgan swept home Jordan Roberts' low set-piece.
Glory's response was almost instant, Circati losing his marker to meet a Jordan Abrahams corner at the far post and apply a clinical finish.
The visitors, however, made the worst possible start to the second half with Sorrento regaining the lead in the opening minute when Teece latched on to Jesse Owuour's long ball and lobbed the onrushing Lee.
Seldon almost levelled for Garcia's side and Abrahams then crashed a shot against the bar and yet it was Sorrento who struck again on 75 minutes when Teece's angled shot crashed against the underside of the bar and was adjudged to have crossed the line.
To their credit, Glory responded well once again and 3-1 soon became 3-2 as Jayden Leader played Seldon in and he fired past James Morgan in the home goal.
With their tails up, the youngsters surged forward in search of an equaliser, but although Jack Leech and Ciran Bramwell both went close in a frantic finale, it ultimately eluded them.
Glory enjoyed better fortunes in the day's other games, however, the Under-18s and Under-20s both securing three points courtesy of respective 1-0 and 7-0 victories.
Sorrento 3 (Morgan 25', Teece 46', Roberts 75')
Perth Glory 2 (Cicarti 29', Seldon 80')
Half Time: 1-1
Referee: Shane Skinner
Sorrento: GK James MORGAN, 2. David STOKOE, 3. Jakub PRAJZA (12. Sam FAULKNER 80’), 4. Shaun KILKELLY, 5. Scott ROBERTSON, 7. Alex MORGAN, 10. Jordan ROBERTS, 19. Jack SALTER, 23. Cameron TEECE (16. Daniel PEARCE 79’), 30. Jesse OWUOUR, 32. Tristian STEVENS
Substitutes not used: RGK Matthew GIUDICATTI, 14 Reece ABRAMS 17 Reece VITTIGLIA
Yellow cards: Kilkelly 42’, Salter 90+2’
Red cards: Nil
Perth Glory: GK Jackson LEE, 2. Zayd FARAH (18. Jayden LEADER 58’), 3. Abias BUKURU (12. Cameron MURRAY 17’), 4. Jacob MUIR, 5. Alessandro CIRCATI, 6. Josh SAMSON, 7. Jaidon SELDON, 8. Jack LEECH, 9. Luke SALMON, 10. Jordan ABRAHAMS, 11. Gomo DUKULY (21. Ciran BRAMWELL 58’)
Substitutes not used: RGK Nicholas SPECA,
Yellow cards: Murray 56’
Red cards: Nil