Glory's hopes of securing a top-two finish were dealt a blow on Saturday when they were downed 3-1 by Newcastle Jets at the No.2 Sportsground.
The visitors took a 1-0 lead into the half-time break courtesy of another fine header from the Westfield W-League's leading scorer, Sam Kerr, but the Jets hit back through Arin Wright, Tara Andrews and Cortnee Vine to secure a win that just about keeps their own finals dream alive.
The defeat, just their second this term, leaves Glory sitting in third spot, but they could drop to fourth if Adelaide get the better of Canberra on Sunday and Head Coach Bobby Despotovski was far from happy with his charges' second-half approach.
"We did not play well in the second half," he said. "Not at all and it was very disappointing.
"It was a pretty even game in the first half and we took our goal well. I thought the girls played well in the first half, but the second half was horrendous.
"I'm not sure that Newcastle are better than us quality-wise, but it looked like they wanted it more and it was exactly the same as the second half against Melbourne Victory [in Round 9].
"Once things started not to go our way, we seemed to want to hide and that's not acceptable.
"We need to calm down now, reflect on the game and then get back on the training ground, regroup and get ready for the Western Sydney game.
"The finals places are all still up for grabs."
After a cagey opening in warm conditions, Glory hit the front on the half-hour mark when Rachel Hill's cross was neatly nodded home by Kerr for her 50th goal in Glory colours.
But the Jets roared back immediately after the restart, with Hannah Brewer and Gema Simon both going close before Wright levelled things up with a well-struck effort from the edge of the box.
Andrews then capitalised upon some hesitant Glory defending to put the hosts in front after 64 minutes, leaving Despotovski's side chasing the game in the final quarter.
Kerr did come close to restoring parity with a couple of headers and substitute Lexie Moreno also fired just over the bar, but it was the hosts who were to have the final word as Vine wriggled free in the box and fired past Eliza Campbell.
Glory have the bye next week and will return to action with another away trip, this time to Western Sydney Wanderers on Thursday 24 January.
Newcastle Jets 3 (Wright 57', Andrews 64', Vine '90+2) Perth Glory 1 (Kerr 30')
Newcastle Jets FC: 28.Britt ECKERSTROM (gk), 2.Hannah BREWER, 4.Libby COPUS-BROWN (11.Cortnee VINE 61'), 5.Arin WRIGHT, 6.Cassidy DAVIS, 7.Gema SIMON, 12.Tara ANDREWS (19.Pana PETRATOS 89'),17.Jenna KINGSLEY, 18.Clare WHEELER, 22.Larissa CRUMMER, 32.Tessa TAMPLIN (25.Teigan COLLISTER 72')
Substitutes not used: 20.Claire COELHO (gk)
Yellow cards: Nil
Red cards: Nil
Perth Glory: 1.Eliza CAMPBELL (gk), 3.Kim CARROLL, 4.Alyssa MAUTZ , 5.Shannon MAY (15.Alexia MORENO, 84'), 9.Rachel HILL, 10.Jacynta GALABADAARACHCHI (17.Liana COOK 45'), 11.Leticia McKENNA (12.Jenna ONIONS 56'), 13.Jamie-Lee GALE, 20.Sam KERR (c), 24.Natasha RIGBY, 25.Katie NAUGHTON
Substitutes not used: 21.Morgan AQUINO (gk)
Yellow cards: Nil
Red cards: Nil