The day after her Aussie team-mate Phoebe Litchfield's heroics in steering Sunrisers Leeds to victory over MI London at The Oval, new Brave skipper Molineux stepped up to show her class in a thrilling encounter at the Rose Bowl.
Fire were in the box seat to hunt down the Brave's score of 126 in Southampton after reaching 1-80 for 58 balls, with another Aussie, Georgia Wareham, scoring nine.
But Jemimah Rodrigues' direct hit to run out Freya Kemp for 39 gave Brave, tournament winners in 2023 and semi-finalists last year, an opening they seized upon.
Georgia Voll holed out for 52 and wickets fell rapidly as Victorian all-rounder Molineux (3-14 from 20 balls) Lauren Bell and Tilly Corteen-Coleman (took two wickets each) ensured Fire were forced to end on 8-118.
Brave had earlier built their total around South Africa star Laura Wolvaardt's unbeaten 45 from 36 balls with Lizelle Lee contributing 31.
Left-hander Molineux was then stumped after a free-flowing 22 as her Australian team-mate Heather Graham's four-wicket haul for Fire proved in vain.
"It was a great win in front of our home crowd," Molineux said.
"We clawed our way back and it was really pleasing... It'd be nice if we could take some catches, but we should not read too much into that and just crack on."