Ainsworth claimed figures of 2-15 at Drummoyne Oval on Tuesday night, as the Thunder were all out for 97 in the 20th over in pursuit of the Scorchers' 7-171.
The Perth Scorchers proved too strong for the Sydney Thunder in their WNNBL clash at Drummoyne Oval. (Steven Markham/AAP PHOTOS)
The seamer set the win up for the Scorchers, taking 2-4 from her opening two overs.
The result ended the Thunder's four-match winning streak and helped heavyweights Perth climb from fifth to second on the WBBL ladder.
It came amid some drama, with one of Drummoyne Oval's light towers going out early in the Thunder's chase.
Umpires stopped play to ask if both teams were happy to continue, before Thunder captain Phoebe Litchfield opted to stay on with the bat.
"I don't think I would like to be batting out there with Ainsworth out there firing, but that's the umpire's call," Thunder coach Lisa Keightley said on Fox Cricket afterwards.
"And they gave it to the players, so that is interesting."
Already behind in the chase after Ainsworth's wickets, Litchfield and Heather Knight offered the Thunder a brief hope with a 32-run third-wicket stand.
But when Litchfield was caught off Amy Edgar (3-19) the innings unravelled.
Sophie Devine top scored for the Perth Scorchers with 48 off 34 balls against the Sydney Thunder. (Steven Markham/AAP PHOTOS)
Earlier, New Zealander Sophie Devine helped set up the victory with 48 from 34 balls, turning around her run of two straight ducks before Tuesday night.
The 35-year-old pulled Sammy-Jo Johnson for one six, cut her for four the next ball and provided a deft late-cut to send Shabnim Ismail to the deep-third boundary.
Devine was bowled by Ismail later in the same over, but with the assistance of Mikayla Hinkley (19 off 9) the Scorchers' win had been set up.
Devine has been one of the world's best batters for more than a decade, but Ainsworth showed on Tuesday night why she could soon enter Australian calculations.
The 19-year-old had last year's WBBL MVP Chamari Athapaththu caught in the first over, before removing her opening partner Georgia Voll in her next over.
She also should have had Hannah Darlington caught in the deep late, only for the chance to be dropped by Lilly Mills.
Ainsworth's wickets saw her add the duo to a high-profile list of victims this season, including Meg Lanning, Annabel Sutherland, Danni Wyatt-Hodge and Alice Capsey.
The right-armer has now taken nine wickets at 12.88 this season, after taking 15 at 19.66 in her rookie campaign last year.
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