Sophia Dunkley smashed a half-century before Melbourne Stars' disciplined attack bowled superbly at the WACA ground to dent Perth Scorchers' hopes of a top two finish in the WBBL.
Chasing what seemed to be a modest total of 158, Scorchers' strong top-order crashed to 19 for 3 with openers Beth Mooney and Sophie Devine both uncharacteristically failing.
Stars seamers Kim Garth and Annabel Sutherland conjured swing with the new ball on a surface that appeared juicier under the lights.
Scorchers were left to rely on England star allrounder Nat Sciver-Brunt to haul them back into the contest. There was extra spice after Sciver-Brunt's controversial signing with Scorchers having not made herself available in the overseas draft where she would have been a retention pick for Stars.
Sciver-Brunt, who had only scored 64 runs in her last four innings, played several expansive strokes to raise the spirits of Scorchers' faithful. But she couldn't kick on after she was stumped on 24 after failing to connect a flighted delivery from offspinner Alice Capsey.
They were always up against it from there despite the efforts from Amy Jones, who made 42 but it was not enough as Scorchers lost their second straight match.
Left-arm spinner Sophie Day rolled through Scorchers' lower-order to finish with 4 for 26 and complete Stars' 33-run upset victory.
A game behind league leaders Adelaide Strikers, Scorchers are clinging tenuously to second spot as jockeying for finals positioning heats up.
Still without skipper Meg Lanning, who remained on personal leave, Stars' finals hopes were already over but they produced a formidable effort.
Stand-in skipper Sutherland elected to bat in oppressive conditions with temperatures hovering at 36 degrees when the game started.
Stars had to initially fend off probing new ball bowling from quick Chloe Ainsworth, who knocked over opener Maia Bouchier in the second over. But apart from Ainsworth's menacing swing, Stars were at ease with Dunkley and Capsey taking control.
Dunkley, particularly, decided to go the aerial route especially against Scorchers' slew of spinners who weren't getting assistance from the benign surface.
Scorchers skipper Devine turned to Sciver-Brunt, who bowled for the first time this season in Scorchers' previous game against Sydney Thunder. She bowled a tight line and length, but Dunkley was in an aggressive mood as Stars eyed a big total at the midway mark of the innings.
Even Ainsworth couldn't limit Dunkley when she returned to the attack and was smashed for a six over long-on as Scorchers appeared to be going through the emotions.
Dunkley sped past her half-century leaving Capsey in her wake. Capsey struggled to regain her earlier rhythm and she holed out to long-on to gift Sciver-Brunt her first wicket of the season.
It triggered a collapse with Dunkley falling in the 15th over before Tess Flintoff was bowled first ball by seamer Piepa Cleary.
The smattering of fans braving the famous grass banks were finally up and about although Cleary was unable to claim a hat-trick. Stars fell away at the backend, but their attack brilliantly defended the total to inflict a costly loss for Scorchers.
