Brisbane Heat 3 for 179 (Johnston 54, Voll 40) beat Melbourne Stars 8 for 170 by nine runs
Player of the match Johnston only got a call-up due to a knee injury to Heat top-liner Grace Harris and she made the most of her chance.
“It was pretty surreal. It was my first hit of the season and I was seeing them like watermelons,” Johnston told Fox Cricket after her knock.
Heat opener Georgia Redmayne and Georgia Voll made handy contributions to lift their side to an imposing 3 for 179.
Stars allrounder Sutherland, who has been in outstanding form with the bat this series, got her side to within striking distance of victory as she took advantage of the power surge before Jonassen’s heroics in the final over prevailed.